all push up really
aston to the north has the only place where a DH bike is worthwhile, but not necessary
some fun to be had at chicksands, 4x, jumps, drops etc
woburn has some good lines for jumps lots of xc
swinley has a few fr type runs but really its xc
north downs has some good stuff, not to justify a dh bike
some good local stuff around hampshire, QECP has some xc stuff and the odd tough line
http://www.gravityproject.co.uk/ run a good race series, check out their venues for mini dh parks , the last race even claimed brendog- he had a quality otb!
tbh youll get more fun out of an enduro bike, unless you fancy a regular 2-3hr drive to cwmcarn etc