My wife and I belong to U3A spotit and it's really great. We have any number of groups, all organised by members. Reader groups, gardening, genealogy, walking, bridge, chess. You name it.
If anyone wants to start a group up they can do that as well. Membership, (in our group anyway), is only £8 a year and when we meet in other people's houses we give a small donation to pay for tea, coffee, biscuits etc.
You belong to as many or as few groups as you like.
So it's well worth looking into.
Good luck to you.