I learnt at Wycombe about 8 years ago, at what was then 'British Airways Flying Club'.
I believe this is now called Airways Flying Club but is to all intensive purposes the same place. I had a great time there and found it a nice place to learn. They're mainly Warrior based.
There's also Wycombe Air Centre (which is now a cabair as far as I know) and is mainly Cessnas. No experience of this one.
Have you had a look around them? If you haven't already, I'd strongly suggest just popping in and talking to them both and see what you think. You might just gel with one or the other or find someone you feel you'd get on with for your training.
Anywhere near London has the same issues in the sense that it's pretty expensive.
There are also White Waltham and Denham near there too. White Waltham is very nice as well. Personally I wasn't so keen on Denham.
Good luck....