I have no experience of Elstree, but also live in North London and recently completed my PPL. I had to choose between Denham and Elstree and opted for the Pilot Centre at Denham.
Extremely good bunch of people and very friendly - highly recommended.
Ditto - word for word, except the North London bit - Watford doesn't really count as London I think. See you around TPC ChiSau (PM your real name and I'll know who to look out for!)
AliB
(Thats Alastair Beadle)