It also says boarding houses too, which are more-akin to caving huts, so it sounds like caving huts opening would be within the spirit of the law. I think from the rules on pubs they are encouraged to take everyone's name and addresses in case anyone comes down with the virus would be a sensible precaution for huts, something for non-members and members in some clubs do already I believe, normally to chase payment.
So first step would be to have a sign in sheet, with name and address. I am on my lunch break at the moment (just finishing) so not sure I can volunteer for anything due to lack of time, it depends what you want and how much time is needed?
Biggist difficulty is maintaining social distancing when everyone is pissed (that goes for huts too
).