PPL: brilliant! My personal recommendation is Skysport, at Elstree and North Weald. Reasons:-
(1) Beagle Pups. Approx 97 billion times better than C150/152 PA 28/38 (NB this has been proven by science).
(2) Instructors who have proper day jobs and do not have ties or gold bars.
(3) Half or full day lesson slots and detailed ground briefings.
(4) Opportunity to hooligan it up aerobatting or air racing in a Bulldog.
(5) Notwithstanding what I've just said, very positive safety culture and well maintained machines.
Drawbacks: transit flying to Duxford for circuits (not really a drawback). Limited instructor availability Monday to Wednesday.
Anecdotal recommendations for SE suggest that WLAC at White Waltham and both schools at Wycombe are worth a look. Shop around: visit clubs, talk to people, kick tyres. Do not get into brown Cessnas full of toffee crisp wrappers. Have fun.
PS I'm a member of Skysport but have no financial stake in it.