From South East London, consider Headcorn. Easy to get to and loads of instructors there. You're bound to find one you like. Plenty to see too, it's a day out.
Biggin is OK, but you could end up paying for a lot of time on the ground, plus all the landing fees. Steep, when your lessons get to the circuits stage.
You'll get your money's worth at Headcorn and there are no landing fees in the club aircraft, which will make a BIG difference to your training costs.
PM me if you want more information.