Trail riding within an hour's drive of London?
Looking for somewhere not too long a drive from London (hour and a half max) where there is some good, fast trail riding to be had. I'm on a 'cross so looking for a happy medium that isn't road, but doesn't require a MTB. Don't mind getting a bit muddy*. Ideally somewhere with a circular route of up to 80k, but not vital that it's circular.
Any and all suggestions welcome!
*like getting quite muddy.