I'm not sure Biggin is the perfect choice for a PPL anymore. You have plenty of options from SE London and I'd suggest 2-3 trial lessons with several outfits before making your decision.
Particularly in the current economic situation,
don't pay up front however tempting the deal.
See if you can track down an issue of Pilot/Flyer etc that has the annual review of flying clubs. By law they have to operate from licensed airfields and a map of these can be found
here to help you work out the geography of getting there for your lessons.