Sadly there are effectively no Green lanes in Scotland, or none worth trying to make a day of it. ( Except the Corrieairack Pass and that's been illegally blocked by the landowners with the connivance of the Council for years.) Pretty much all off-road activity is by agreement with local landowners, estates and the Forestry. 

...but if anyone does venture into our dark northern fastness I can and will offer camping space and if I'm about, we might get a bit of a trundle ...given I have a couple of useful keys and friendly local land-owners :-)

I also organise Green Road Runs for SLROC and S2C but you'd need to be a member of an ALRC Club for Insurance purposes.

Might send you the maps Prof, still got Cumbria high on my agenda.