@Delilahhhh the council run classes I went to were definitely better for actually socialising - they tended to have volunteers to help as well as a leader or two, which is brilliant when you have DTs! This is pre-Covid though, things may have changed since then (obviously my DC are too old for such classes now!) but the groups were cheap, convenient and lovely for meeting people.
@Alalalalalongalalalalalonglonglilong you've reminded me of a class I once tried out... it was advertised as having plenty of parking at the venue (community hall) which was great, as obviously with twins you can't just carry your single baby into the class, you have to get the buggy out etc. Well, there WAS plenty of parking but only if you got there a couple of hours before when all the other classes started at the hall, otherwise you ended up driving around waiting for a spot
having finally got a spot and wrestled the DTs into the twin buggy, I went up to the hall only to find that the buggy wouldn't fit through the door, and of course no one could come out to help me as they were all in the class which was out of sight round a corner inside!! I gave it up and went to have a coffee nearby instead...
Emailed the class leader later and explained what had happened, and her only reply was "Oh what a pain"... no apology for the lack of info, no offer to help next time. And no, she didn't refund me for the trial class! On the bright side, I didn't sign up for her classes so it saved me quite a bit 
(To anyone reading this thread, I would say that 95% of the classes I went to with my DC were absolutely fine and I would encourage you to go, but the ones which stick in my mind are the ones which were a bit disastrous!)