Not sure if this has been said before, but make sure you can rent the type you are training on. Ideally this will be renting from the same people that did the training.
There are places doing dual on Robins for not much above a hundred quid, if you are happy to drive a 90mins or so from London.
Otherwise there is indeed the S2A at WW. I've had the privelege of being slapped on the back of the helmet by Alan... he's a demanding but friendly instructor and has a truly deeper understanding of aeros than anyone else I've met. If you don't fly with him, then definitely buy his book.