If you can stomach the cost of UK schools, there are a couple of possibilities right down the road from you:
The Pilot Centre, Denham - good school with good fleet of PA28/C152/C172. Good value for money for the area and a decent instructor pool with an excellent CFI.
Elstree Aerodrome - similar social demographic to Denham, rather rich London clientele and a slightly attitude challenged FISO (but don't let him put you off!) Several schools on site - Firecrest looks and sounds OK. Do a search, as there are several enlightening reports on Flyteam and Cabair...need I say more..
Good luck.