With so many forest roads blighted by traffic in the holiday season, it's a very good idea in principle ... but I'm not sure it's really practical.
What if say you ban cars from the ornamental drives. There would be a parking bottleneck at Bolderwood and Brock i.e. at each end, instead of cars being scattered at the numerous little car parks along the way. Exclude or discourage cars from the whole forest and all the area round the edge will be a nightmare!
The idea also seems to ignore the fact that the forest is not a theme park, it is a living, working place like any other. Off the top of my head I cannot think of a single forest road that doesn't have at least one house on it. Will the friends/family/visitors/suppliers of these residents all be barred and/or taxed? How is that going to work or be fair?
Furthermore this kind of tax is surely going to discourage those with low incomes but will hardly register on those 'problem drivers', for instance the ones with the large expensive 4x4s that ooze aggression to other road users.
Unless we change national attitudes towards alternative forms of transport then Mr. & Mrs. Tourist are going to arrive in their car. If they don't come to the forest then the multitude of businesses for which they are the bread & butter will suffer.
I'm all for it in principle, I just don't think it would work.