I can probably help as I spend a lot of time down holes on Portland. You'd be very welcome to join us. Do a fair bit of digging but also happy to show you around the place. Always looking for more people to help on our mad projects.
Be warned, in comparison to Wales you may find some of the caves a little disappointing. Plenty of fun to be had though.
Best email me direct - firstname.lastname@example.org and I'll let you know what we're up and when.