Yep ask your CMHN, usually they start around 6 weeks and will be at the place that you go for your visits.
They should organise you into one, but if not you could look at the playgroups website and see if there is anything local in your area...
At the playgroup that i go to there are babies that have been there from birth, its a musical one, so its for all ages and stages, the babies just get sung to, the older ones sing and dance and the Mums can bop around

where are you located?