Well done Betsy, I'm afraid my youngest grandchild is four and a half, but goodness knows there are enough mums around...well done. And anyway come and join in to some of our activities. Where do you live? Se1 is pretty big.
Welcome Have a look at the social section of this sites, There is a bumps and babies club which i think is exactly what you are looking for. and why not look at the other activities for non baby focus social interaction, such as stitch and bitch and book club. You will soon be making lots of friends in SE1:)
I have a nine month old daughter and I found loads of local things to do and lots of mummy friends through the yahoo group called Borough babies. I would definitely recommend joining up, we also meet every week for coffee and new comers are always welcome.
Join riverside parents (riversideparents.co.uk) free local group. We run a soft-play session at Downside centre 3 times a week for any kids under five. We have an area with mats for babies too. Details on the web site. Welcome to SE1 - best place in London to live with kids!
Borough babies yahoo group also very good for ideas.
You could try the Horniman Museum, they have regular activities at weekends. Last week my friend took her little boy to a kite making session, and afterwards they took it into the gardens and they flew it - it actually worked! The museum itself is very child-friendly too.