Hi nxb1,
VCGH used to have a very active MTB side (I used to be a ride leader), but a lot of the regulars stopped, for one reason or another, so it’s less active these days. There’s still a small group who organise rides on Sunday mornings from Godalming, but it’s mainly via their facebook page(not the VCGH facebook page!). I suggest you contact Jules or Roland, as they are the main people who organise the rides these days. There’s also some route maps that you can download from the website, if you fancy exploring by yourself.
There also Three Counties MTB group.
Greg