That video on iplayer is brilliant! I'd love to see terrain like that in CloD.
Interestingly though, my book on the BoB film explains that a lot of the footage was shot over France (because the weather in Blighty was too poor for filming) so I'd take everything there with a pinch of salt (as far as modelling England is concerned)
Ali, do you have access to the textures which the trees sit on? Maybe darkening those would improve things?