I've met some lovely mums at baby group. There are groups within the groups but not cliques. People with similar aged babies tend to sit together (which is good so the older babies aren't clobbering the newborns) but everyone's friendly enough. I tend to think if you don't want to talk to me I don't want to talk to you so I don't let it upset me there (massive change for me as I was such an anxious worrier pre-DS).
My friends and I have a lord of the flies situation going on, we let them govern themselves
Not really but we don't get upset/shouty about a bit of hair pulling/shoving as they're all so tiny. It's a oops sorry, he'll get him back next week and move on vibe!
That said the groups I go to are split into non-walkers and steady on their feet, so no marauding 2 year olds. My friend's little boy is not at all like you describe, my nephew is (as BiL spoils him rotten) but luckily as he gets his own way at home he's completely taken aback when other children don't let him get away with it and so is a perfect angel at nursery/play group!
Told you she can sense weakness WL, on your "I-mean-business" days she knuckles under!