Hi Phil,
I would direct you to the Directgov.uk website, as it's quite useful and user friendly.
Broadly speaking (and I work in corporate, not personal tax, so use this as a guide, but not as law!), as your wife is a citizen, I can't see why your status would prevent her from applying for the various tax credits (they are typically paid over to the mum anyway).
In the event that neither of you are working, she can certainly get the Child benefit, which is around GBP81.30 a month - if you do get a well paying job by 2013 (ie, if either of you are a higher rate tax payer by then), this is one of the places the government is cutting the budget with, so that is going for those people.
There is also the child tax credit, again, this depends on income levels, and if either of you are working (I think it's 16 hours a week - but I haven't got my tax guides with me at the moment), there is the working tax credit.
There is also help with childcare costs for working parents, and once your child is 3 (2 if you're considered sufficiently not-well off), the government provides an education grant which is paid directly to the childcare provider, and covers 2.5 days a week of childcare during term time. My childcare provider simply apportions this across the full year and reduces their fees.
Once you are working, you may be able to join a salary sacrifice scheme for childcare vouchers (presuming you use childcare), which allows you to sacrifice a restricted portion of your salary tax free to pay your childcare provider - the amount of sacrifice is dependent upon your income level.
Those are all the ones I can think of - hope everything goes well!
Kind regards
g
