If you jump back 30 years most children didn't have any socialising outside of cousins etc, and we all turned out ok.

My ds had weekly playgroup and a weekly kindermusik class but that was all till he was 2. He now goes to pre-kindy 1 morning a week and swimming once a week and that's all. He is a sociable little boy so he hasn't suffered from not being in more regular contact with other kids.

Playgrounds are the best place in my opinion... and they're free!