Firstly, no job is worth destroying your health for - and I know far too many unhappy academics who admit that the constant rejection and criticism is really wrecking their mental health and who wish they had jumped ship rather than assuming they'd eventually get a thicker skin. And let's face it, however much success we've had, that one really mean reviewer or ob rejection can knock self-confidence a lot. Do you have any sort of sense about whether it's the lack of long-term certainty or academia in general that's really getting to you at the moment? That might give you a clue of what to do.
It must be incredibly frustrating to be doing everything right but not getting anywhere. Does looking at who is getting the jobs give you any clues? If eg as a quallie you're stuck on the wrong end of a hiring market that wants quants? Or an unfashionable area of expertise? If you were getting interviews, I'd say you'll get there in the end but the no interviews with what sounds like a strong cv makes me wonder if the market is working against you in some way. I don't know Australian sociology but i'm also a social scientist and know for my subject some australian departments are obsessed with mimicking US trends, which is bad news for quallies.
To some extent yes all jobs have their downside but there's a special something about academia and mental health that stinks. You might indeed be happier in a different field. Maybe even charting the possibilities would give you a sense that you were regaining control over your future? Final thought does your university offer dedicated career advice for postdoc researchers? Mine does, it's good and few people take up the support. It might be worth a try if it exists.

Might an EdD programme be a good fit with what you want to do - it seems to be manageable alongside a day job and more connected to praxis (or so a friend with one says).

Forgot to add - a lot of these complaints are targeted at the wrong person and so cause zero grief to the guilty party but a lot to people who had nothing to do with it.

Suggestion: complain yes but not to the department but to the administrator's line manager and make it formal. Students tend to complain about the department but academics have no power over administrators.

Interesting I didn't know the 3.5 model could be used for methods training. We've only tried it for PhDs needing difficult language learning but maybe the DTPs differ in their interpretation of what they'll fund.

For the social sciences a masters has been expected for the last two decades. The ESRC made it an expectation in the late 1990s I think, when they started funding research methods MA/MSc programmes.

But are those not attributes that if possessed should have produced 2:1 / merit results in the earlier degrees given how few don't manage to get a 2:1 nowadays. That's how unis tend to see it anyway.

Couple of points:

1) Do you actually possess the intellectual copyright to your results? I.e. where is your funding from and does it involve a grant gained by the former advisors? It might not be as straightforward as walking away and saying you're not being on my papers as I've fallen out with you.
2) Is the person acting as your named supervisor willing and able to put intellectual input into your thesis? It sounds like they've only agreed to act as a glorified personal tutor. You seem to be taking it for granted but again might not be as straightforward as you think. The odd set-up she's insisted on does make me wonder whether she can go beyond her current role.
3) I would encourage you to reflect on DrCorinne's posts carefully. You sound extremely confident that you will walk into an academic career but the reference question is an issue, as if the supervisor has no intellectual input into the thesis then it will limit the sort of reference she can write and its credibility.

Your marks coupled with a decent proposal and a feasible choice of supervisor would be enough to get you a place, I think. You are, I'm afraid, right that you are unlikely to be competitive for funded places. In the areas you mention, the vast amount of funded places are through the AHRC (philosophy) / ESRC (politics) Doctoral training centres / partnerships. These are competitive and in my region (not geographically as desirable as some), we're not seeing any success for students with neither a distinction at MA nor a 1st at undergrad. Compared to the sciences, there are so few funded places, that it's ridiculously competitive to get funding. (And there's the same issue at the end - far fewer postdocs). But that means that you would need to get even further into debt for a qualification that statistically is very unlikely to result in academic employment, and as others have said may not be so valued by non-academic employers.
If you'd had some experience of professional level employment and thus had the skills and contacts to give you a route back into non-academic employment, and really wanted to do a PhD at all cost, then so long as you went into it fully informed of the risks, then fine. But in your case, you might end up no better off in employment terms but with more debt. Is that a risk you are willing to take? Or might it be better to at least giving changing job, to something that stretches your brain more, a shot first, in case that makes you happy? There's no time limit for starting a PhD if you become certain that it's the only route for you.

OP I hope you had a constructive meeting with your supervisor. There are many examples where students have turned things round from this point and nobody ever asks what the original outcome of the viva was - they're only interested that you passed.
A couple of suggestions that your supervisor might already have made:
1) put the report out of sight for a week and be nice to yourself. You are almost certainly reading the worst possible interpretation into it now. When the immediate hurt has calmed a little, then making a plan is easier.
2) I'd suggest starting a big chart - the items that need addressing on the one hand, and action points needed to achieve them on the other. Try to break it down into detailed tasks. You must feel overwhelmed and it can be much more manageable if you see lots of small tasks rather than rewrite theoretical approach chapter.
3) Then decide a logical order. Do you need to go back into archives? If so when would it be possible to do that? From that perhaps agree a schedule with your supervisor about when you will revise each chapter.
4) Try to keep moving through your tasks steadily. Just because your uni has 18 months rather than the 12 months others do in this scenario, doesn't mean you need to take 18 months. You've clearly got a lot to do, but if you get started after a short break, then the sooner it's over. The people who struggle with an R&R are generally the people who put off starting the corrections.
5) It sounds from your description that you've maybe used a theoretical framework your supervisor wasn't familiar enough with - it might also be worth considering whether anyone else in your department could help advise / check that bit of the R&R so both you and your supervisor feel confident about the re-submission.

Here tutors are forbidden to communicate results to students before the official release date - it's a disciplinary offence.

I work in a faculty with the same entry requirements as Birmingham. We are not allowed to accept a student with your grades without special permission from the dean, who very rarely agrees. This is because the statistics tell us that such students rarely manage to complete a PhD. I think you need to be really honest with yourself about how much the earlier degrees really reflect your abilities - it's hard to wave away two degrees with similar outcomes. If you are convinced otherwise then one way might be to do a second research methods focused Masters and show that you can achieve.

Netherlands is https://www.academictransfer.com/

https://euraxess.ec.europa.eu/ might be of some use. Also is there a European Association for your subject area - mine at least has some postdoc listings on its website. But I don't think there's really a pan-European catch-all site. Perhaps if you posted the countries you're interested in, then people might know the jobs.ac.uk equivalents for those countries?

It will depend on your own behaviour. If you try to manipulate your fellow students and most importantly your new supervisor into having negative views of an otherwise well-liked individual, then the consensus will be that you are the problem. If you behave professionally and don't throw around dubious mental health diagnoses like in this post then it will be fine. Your fellow students will probably gossip but I doubt most of the staff will know or care. And if the supervisory relationship had broken down, your former supervisor is quite probably cracking open the champagne, rather than plotting against you, as there is nothing worse than the hours and days trying to get somebody over the finishing line, who you know loathes you. Honestly PhD students are always convinced that they are the centre of staff discussion and lives - they really aren't. Colleagues elsewhere provide far more entertaining gossip on the whole.

And sorry if this sounds harsh but as there are many people posting on this forum seeking support with major mental health problems, please cut out the dodgy mental health diagnoses about your supervisor. It's not necessary or appropriate and may put vulnerable people off seeking advice.