Your tax credit award is based on 2 elements:
- combined salary if you both work over 16hrs/wk
- weekly childcare cost
If you go back to work for the hrs your state, and your partner also works over 16hrs per week, plus your total household income is approx 60K or below (i.e. most people!!) you will get an award based on your combined household income.
The additional award for childcare costs only applies if you're paying over a certain amount per week for childcare (I think it's about £90?). As I was only paying for 2 days' nursery per week for DS (before I went on maternity leave in June), I wasn't qualifying for the childcare cost element, so the only amount I received was based on our joint income.
Therefore, as you will only be paying childcare during the school holidays, although it's worth declaring the approx total you pay over a year, I doubt you will receive anything as, averaged over a year, this will be below the £90 per week threshold.
The only other thing I can suggest is to ask your employer whether they do childcare vouchers to help with your holiday care costs as these will be free of income tax and NI i.e. you will pay less compared to paying for care in cash.
Sorry it's a bit long winded but hope this helps!!