Many thanks Jp and Paj - good advice. Blair Adam forest is just a mile down the road from me and there's always loads of off-roader's blatting about there - usually being chased by the rangers. It was seeing them that reminded me how much fun it used to be and put the idea in my head. I think I'll go hang around, at the risk of looking like some wierd stalker, and see if I can talk to any of them.
I'm also not far from Knockhill track and they sometimes have 'meet the expert' type days so will keep an eye on the events diary.
Quite like the look of a YamTT250R to start with, if I can pick up a decent one that's not too trashed. Luckily, I live in a farm cottage, in the middle of 500 acres so have plenty opportunity practice and terrorise the wildlife.......