have you put your details as you think they will be if you go back 4 days into here?
If your not entitled to tax credits, there are childcare vouchers, which a lot of employers will supply. Both me and DH claim the maximium £243 a month, and then this is tax and NI free. One of the companies give savings information here - but the company it is run through is determined by your employer - so DH and I both get vouchers from different companies. The savings are the same tho.
Is your job a monday-friday 9-5 type role? If not, could you do one evening and one day at the weekend, along with 2 "days" to minimise your childcare costs?