Agree with all the comments so far.
By far the most important, IMHO, is the intangible "feel" - go into all the schools within a reasonable distance and talk to people. Bad weather days are usually the best time - there will definitely be instructors on the ground, and you can probably find a few students around the place too.
White Waltham might be a bit far from you, but I'd definitely recommend them if you don't mind the drive - that's where I did my PPL, and where my current aircraft is based.
Good luck, and have fun!
FFF
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