London flying
Before you commit yourself to any one flying school check out the prices in detail, if you get a very low price then it probably was a whole host of "add ons" (landing fees, fuel surcharges, briefing fees & VAT).
What you have to establish is the real price per hour, not the headline rate!
To help you I will recomend three companys that are honest about pricing, all are within London public transport & a short taxi/bus ride.
WLAC at White Waltham
BAFC (or is it now AFC?) at Booker
SFC at Stapleford.
Talk to these people first to get a benchmark, once you start phoning around the others and asking questions about pricing structure you will no doubt retun to one of the above for your lessons.
My recomendation would be BAFC at Booker (01494 529262) but all the others I name above offer value for money quality training.