There are some cracking deals about at the moment, but more on new than used. I went past my local Vauxhall dealer to see a new Corsa for £189 deposit then 60 months of £189 and the Peugeot deal where everything is included in the monthly, you only put fuel in it!
Also, if you take it on straight hp, you can settle it early and over pay without any penalties.
The pcp's only really work with new cars, but are a good idea if your going to change every few years and keep paying the monthlys.