London Transport Flying Club
Chewy,
Any school you care to attend, whether in the UK or overseas, will almost certainly have been the subject of posts on this site.
I therefore suggest you use the search facility and you should come up with a wealth of info on any school you care to name.
I strongly agree that doing PPL overseas and all in one go is best.
However, if you find you do have to use the UK schools afterall, I suggest you should take a look at the London Transport Club at Fairoaks.
It used to be for London Transport staff only, but now it is open to all. I'm not a member and haven't visited them for a year or so, but they used to have some very good flying rates bearing in mind how close to London they are.
Best of luck,
Broomstick.