Obviously it depend loads on what you earn... But you should have two amounts, one of which is Working tax credits and the other is Child tax credit add them both together and thats what you should have each month. The paper work they send you can be really confusing!
Im guessing you get DLA for the baby? It does makes a huge difference in the amount of child/working tax credits you get if you are on middle or high rate DLA But if its low rate you dont get any extra. Im fairly clued up on both if you want any help feel free to pm me

We've only just applied for DLA (well, just before Xmas), and it takes 8 weeks or so to process the application. So I guess there is correlation to be done there in due course.
Its just the figures on the documents that HMRC sent me are so random - apart from the info on earnings I gave them - they make no sense whatsoever to me. I guess the only way I'll understand the figures is to call them.
And don't ask me why it takes 12 weeks for HMRC to process a simple application for child benefit......heed this news parents to be.......