Hayley, exactly what Slyder said, don't be so hard on yourself about this. At least you are being honest in realizing that you need the extra money for the mortgage instead of just ingnoring it and the situation turning ugly with trying to make ends meet cause that in itself can lead to relationship problems.
TBH, you will probably end up enjoying the 2 days at work.. I also don't think that there is a right or wrong time to start childcare because everybody's situation is different.
Best of luck..