Try www.fly2help.org
Have a look at fly2help.org They have a Chipmunk and Super Decathlon. Their instructors are hugely qualified (2 of them also fly Spitifres!) and many of them have displayed high performance aerobatic aircraft before. Two of them even own Pitts's......... They operate out of Kemble [not too far from you] and the other plus point is that all their profits go to charity (helping young kids experience flying and funding aviation scholorships)
cheers
Phill