If you don't mind an hours drive, you might find it well worth heading up the road to Popham.
Lots of groups, at just about every type and price bracket imaginable (well, so long as it's fixed wing and single engine).
I'm sure there is a zero-capital group somewhere in the south of England, but frankly I've never met it. I doubt anywhere you'll get away with putting less than £2k in for a group A share.
G