Things in the arts and humanities are a little different. Here a PhD is virtually a prerequisite unless you are extremely well published or possess significant industry experience. You will also need to be able to demonstrate the ability to teach. There are a few different routes into PhD study but keep your eye on THES (http://www.timeshighereducation.co.uk/) who advertise for studentships. The usual arrangement is a stipend for around £10,000 a year where you will do between 6 and 8 hours teaching per week, plus your PhD of course!
My route:
1st Class undergraduate degree in arts related subject from decent uni.
Postgraduate course plus industry experience in advertising (running my own business)
Got fed up and fancied the freedom of PhD study.
Publish like crazy
Get good job (with intense pressure to research and win grants).
Unlike the sciences, in the arts it doesn’t matter quite so much where you do your PhD. Of course a PhD from LSE is going to look better than London Met’, but it really is the quality of your publications that count.