Am I missing something?

[Tiredprobably]

I'm a sahm with an 8 month old baby, my maternity pay has now finished and I'm not planning on going back to work. I know I get child benefit but is their anything else available? My partner earns quite well but things are tight as he's self employed, so wages are very changeable.

You should fill out the form for child tax credits. My dh also works and I'm a sahm. We don't get much from child tax credits but every little helps.
I've been told by friends to claim jsa, but tbh until I'm actually job searching some time in the future, I don't think it's right.
It's definitely worth filling out the ctc form though. Don't be put off by how rude the people on the phone may be, some seem to have the attitude that you're stupid, insignificant and a bum-it is hard not to get angry with that attitude. That said, some are very pleasant and helpful.
If you google child tax credits, it should take you to the .gov website which has the numbers and stuff.

Thankyou Jen I'm the same don't think it's on to claim jsa as I'm not trying to find a job and we are not too bad at the moment!

The ceiling for WFTC is quite high, have a chat, being self-employed your DH can use the figures from last years accounts. If he made a loss or less than £16k you can get quite a bit of help, even if he earned a bit more you'll still get something.

I found the helpline fols to be very helpful, although some are friendlier than others, must be a pretty crap jobs some days if you think of some of the rude muppets they have to deal with. ( not us naturally! )

I'd recommend that you run your circumstances through the Turn2Us Benefits Calculator as a first step. It's a very good resource and will let you see quite quickly if you're entitled to anything including Working Tax Credits, Child Tax Credits, Housing Benefit etc.