Hi OP sorry didn't get a chance to respond again yesterday.. hopefully I can answer your queries as below:
what is the likelihood of getting work, is there a spread of roles across the UK, and are there any prerequisites?
There are lots of PM jobs (advertised and not) around, at various levels and in a wide range of industries. Once you've narrowed down your industry I would approach a number of specialist recruitment agencies as well as prospectively submitting your CV to some key firms in your field on the off chance they are looking. In my company we very rarely advertise vacancies on our webiste, usually recruit from employee referrals, linked-in and CVs submitted to us by people interested in working for us. In terms of pre-requisites, you will need to demonstrate you understand the project life cycle phases (see APM site) and show how you have experience in these. Depending on the level you are applying for you may also need real experience in that sector.
What's the difference (except price) in the Prince2 entry level qualification, and the APM entry level course? Is one better regarded than another?
I had to answer an exam question on this! The short answer is that neither is better than the other. Again it very much depends on the sector you are going to work in. For IT and public sector work (govt, health care, rail etc), Prince2 is the preferred accreditation. For blue chip company work they are less fussy, but like APM as a minimum. I couldn't say for arts/events management.
Would you recommend doing a qualification before looking for a job?
Tricky one. Because the qualification requirements are so specific to job role/industry I would research very carefully before signing up to anything. You don't want to do an Masters in PM for Construction (like I'm doing) to work in retail!
My top tip is to be quite open minded about the industries you might consider working in. I am an arts person, but work in engineering. I know lots of linguists working in finance, etc. Don't feel that you have to stick to the arts sector (which is notoriously tricky to find jobs in). Be as open minded as you can and be willing to embark on a steep learning curve and most employers will be happy to support you. I entered the engineering world with an arts degree and minimal experience and now have a relatively senior position, with a company sponsorship to do a job-related Masters university course and a looming promotion. When I left my arts degree I took the view 'I need a job, any job, to pay the bills and if I like it I'll forge a career from it'. If I'd have stuck to waiting for an arts position I have a feeling I'd have been working in Asda for a lot longer until the 'right' position came along.