M11/M25 that would put you near Stapleford if I remember correctly, I am fairly sure there is a flying school there but do a search on the net.
I did my PPL at Elstree, there are two schools, cabair (where I trained), which offers very good training but at a proportional price, Firecrest is the other company and they run a fleet of Cessna's as opposed PA28's.
If I could have done it again then I would have gone to the US and done a 3 - 4 week PPL course at Naples in Florida. Including flights out there and good accomodation it would have worked out a huge amount cheaper, and you can rack up some cheap P1 hours while you are out there, which always come in useful when you go to share group aircraft and so on. Do a search for Florida training on this site and there will be plenty of information to help you consider doing it that way.