there are a few schools out of Elstree.....cabair are a big player, well established etc but on the pricey side. good equipemnt though. however, when i went over to check them out, i found them very standofish. you may want to look up firecrest aviation though.
stapleford is very well recommended and i know a few atpl guys who started on that route.
personally i'm doing my PPL at from pangshanger (mainly for the location as its 10 mins drive from both home and work).
as the UK weather is ****ty i'd pick the closest place to get the PPL and then move up from there.