I found the first 1.5 years really hard too. I was placed into a mums group that was run by the council, but I wasn't placed until my baby was 3 months old. Then after a few months, quite a few mums either moved away, or went back to work. The playgroups were all at the wrong time for my baby's sleeps, so I tried a music class and a gym class, trying to socialise my baby and to meet other mums – nothing seemed to work! It wasn't until I eventually found a playgroup that had a time that suited us, and started going there, that I found some really nice, friendly people.
You're so right about the "dating scene" analogy. It's like dating for friends. So hard and society doesn't really support the notion!