TQ, I haven't worded my post well to be fair.
I didn't mean to talk about personal failure to secure a funded position. I was talking in the context of a post which didn't have funding attached to it in the first place hence the need for a loan.
I think I am happy to stand by that comment but I made a dog's breakfast of my original post.

It's sending a strong message that your research is not valued enough by our society to bother funding.
It's not a great place to start a PhD from.

If you are prepared to stay away from city centres and London, don't have a car, have no dependents or debtand are prepared to flat share, it is absolutely possible to live very comfortably on less than £10k per year.

£25k would give you about 60% of that so you'd need a part time job as well.
Honestly, if you can't get full funding for your PhD you really need to take a step back and listen to the message the system is telling you. I would personally never take out a loan or self fund.

I have to say that it would be a bad idea to do a PhD on top of a part time job never mind a full time job.

During my PhD I easily worked more than 50 hours per week.
It's not just the number of hours though, it's getting contiguous hours to stop yourself spending the next week refreshing your memory of last week's work. Ideas come to you at all hours, not just the weekend or during 9 to 5 and you need to be prepared to drop stuff on a whim. It is all-consuming.

Personally I would recommend full time on the PhD and no outside work or you will struggle to get anywhere.

I wouldnt waste any time doing a job I didnt like.
Do the masters if that is what excites you.
Life is too short.

No idea why this has resurfaced but I have to say I don't know which type pf person I loathe most:

a) Idiots like this academic who spout these crap "jokes".

OR

b) those insufferable PC advocates who seek to control and dictate what people think and say, making endless shrill and tedious demands for absolutely meaningless public apologies in the mistaken belief that they are somehow making a difference to genuine discrimination out there when in fact they are simply making things much worse for real victims. All this shrieking for attention makes it very hard to hear the real victims who need our help.

A few thoughts here.

It is almost impossible to fail a PhD these days. Pretty much everybody who makes it to the end and submits a thesis will gain the doctorate. These days it is less about demonstrating academic brilliance and more about other skills. With a first class degree you are in a good place to do a PhD. You will face a cliff wall in terms of the step up but you have already demonstrated you can do this at undergraduate level and people who do that have the best chance of succeeding. You will be amongst a great many other students who have a much weaker baseline than you.

You mention your health problems as a reason to go part time but if you additionally work 18 hours a week you are essentially full time anyway. If you can get funding, it might be better to consider full time on the PhD.
If your health problems are mental health problems then I would highly recommend you get that sorted before starting because your resilience will be tested probably beyond anything you have ever experienced. This forum is full of people who have been broken by the experience going back many years.

Your idea neednt be complex. In fact there are huge advantages in seeking simple solutions. I solved some problems which turned out to be simple which was great, but then i finished with a complex problem which was so difficult to solve that it almost broke me mentally. I have never been so relieved to see something get published and off my desk. Whilst I am glad I did that work, i could have got the PhD without it. Your ideas just have to make enough of a difference to the body of knowledge to be worthy of a PhD. Prospective supervisors will let you know what standard you are at.

As for the PGDE, dont waste your life pursuing something you dont like. Its not worth it. Better to be poor amd happy than well off and dreading waking up each day.

I usually assume that if you have made the interview, then you are on a level playing field at that point with everything to play for. Unless there was a tie (there rarely is in practice) you can forget the application process and yor grades now and expect it to be based on the interview.

I would expect the person who performed best at interview will be offered the position.
This is what happens in industry. Of course academia is a law unto itself.

It's a total no brainer. Say yes.
You'll get your first authorship in good time.
To remain in academia you'll need publications.
This is a good chance to get a score on the board.
My first paper was 2nd author. A series of 1st author papers followed.
The order is irrelevant.