I have recently completed an MA in Social Science Research and am interested in applying for a PhD but simply don't know where to begin. For personal reasons entirely independant of the university experience or the workload I didn't enjoy my Master's year and, although I was awarded a Merit, do not feel confident in my own ability
I have a vague idea of the area of research I am interested in but am unsure of how clear I need to be on research aims when contacting potential supervisers. The whole application process seems incredibly daunting and I don't feel that there is much support available for this period. Any advice on how/when to apply and what to expect would be appreciated.

"applying for a PhD but simply don't know where to begin. "

First step: you write your name on an application form.

By the way, if you didn't enjoy your masters chance are you won't enjoy your PhD.

I think at this stage it is important to talk clearly and honestly: Do you really want to do a PhD?

think about it. Then come back.

Hey.
Don't be too put off. Feeling you would like to do a PhD means that you wish to pursue a career in academia, exploring new ideas and making discoveries.
Okay, so you are attracted to this broad concept. Now what you need to do is find one research area to focus on (e.g. politics, sociology, etc), decide where your interests lie in this area, read as much relevant information as possible, narrow your focus, come up with a creative and new idea, narrow the focus again, then bang together a proposal.
Having an objective outlook is the most essential criteria.
You might find it helpful to seek the advice and support of former lecturers if you can.

In my opinion, it is actually quite useful to think long and hard whether a PhD is the right decision. Being put off would be, after all, a good thing in case a PhD wasn't the right thing to do. If that makes sense.

Talking to former lecturers could possibly be problematic as some of them are depressed in their profession but naturally unlikely to admit it to themselves - or to prospective PhD students. Not all of them, of course, but some clearly are.

Actually, I wish I would have thought very long and hard before I put my name on the application form nearly four years ago. I was lucky to get through it but I paid a high price. Lucky escape but I was nearly trapped.

If you feel, however, that a PhD and a lecturing position is all you want in life and if you are aware of the demands, then pleas ignore what I said. Because I can only speak from my own narrow perspective which does not represent the majority of current or former PhD students.

i agree with the point about depressed lecturers: i discussed the issue with lecturer from my undergrad course who said he didn't doubt my ability to do a PhD but his made him want to die !!
my reasons for disliking my MA were entirely personal and did not reflect the actual experience of the course itself. Due to personal circumstance i felt that my mind, and my energy, was directed elsewhere and that i was unable to focus fully on my work.
Unfortunately my supervisor has now retired but there is a lecturer at my former institution (who i very much doubt will remember me) with similar interests to my own. Is it worth a speculative email to pick his brain, even when i have limited ideas at the moment ?

Definitely, sending an email wont do any harm. In the worst case, he wont reply but I'm sure he will. Academics usually feel honoured if someone else is interested in their own narrow area of research...