1. When you go on maternity leave you will be entitled to Statutory Maternity Pay for up to 39 weeks. This payment must continue even if you are made redundant during the 39 weeks, unless you start work for another employer.
2. For Tax Credits, the first £100 per week of your SMP is ignored - the rest is treated as income.
3. If you are not working you will not be entitled to the child care element of tax credits.
4. Your tax credit entitlement for the 11-12 year will initially be based on your (& your husband's) incomes for 10-11 - which will be more than in 11-12 as you will be on SMP for at least 3 mths of this year. After the year end, when you do the annual declaration, your entitlement will be re-calculated to be based on your actual 11-12 incomes, & you may have been underpaid.
5. I calculate that, while you are unemployed & based on your husband earning £12K pa, your entitlement to Child Tax Credit should be about £108 p wk, & Working Tax Credit about £45 p wk. (But do your own calculations & see what they come up with.) This should be the position in the 12-13 year but in order to get this amount you will have to ask Tax Credits to put you on to a current year basis. (If you do not do so, you will be paid on the basis of your joint 11-12 incomes & may well then be underpaid until the next annual declaration is done.) The problem with this is that if you then get a job during the year your income will go up & you may have been overpaid tax credits - which would be recovered from your payment for the rest of the year.
5. Do remember to let Tax Credit know as soon as anything happens which changes the situation - you stopping work; baby being born etc.