Fuji Abound,
You dont say what altitude you normally fly this route at (which will alter the "land clear" guesstimates). You mention
the open country side beyond Welling
but being a local and having flown over the area I believe the nearest open countryside would not start before south of Bromley or east of Dartford. However there are some Parks and school playing fields in the area which could be used in an emergency. I thought Thames Radar liked to keep OH Bexleyheath/ Welling clear so that they can vector Aircraft onto the ILS for Biggin Hill. I normally route South - North just East of Dartford and up towards Stapleford etc. so any tips on using the route you describe would be appreciated.
Thanks & Regards,
cpl4hire