Jimbo,
I only moved down here from Newcastle, so am an accomplished cask ale drinker!
I must say that Newcastle is better for cask ale as there are more micro breweries in the area & loads of freehouses in the city.
Having said that London seems to be getting better than a few years ago when everything was either Fullers or Youngs.... plus there are now a lot of new "craft beer" bars to enjoy!
You got anywhere cold to ferment the lager, or you going down the fermentation fridge route? I'm looking to get a fermentation fridge to get a bit of control over my fermentation temps; the neighbouring flats must have their heating on full all the time so its just too hot for me to ferment at the moment!