I think you will find that the £7 fare on National Express will only get
you as far as Stratford (for the benefit of the OP, this is in east
London). The National Express fare to Golders Green (north London) is
£8 and to central London £10.

I try to avoid Nat Exp at all costs, but as they run both the train
service, and the bus service to Standstill I haven't got much choice,
what are the buses like are they reliable due to traffic?
--
Joe Patrick
Railways Online - for GB railway news, information & photos
http://www.railwaysonline.co.uk