I guess one of the major factors to take into consideration, is are you going to be bringing in any extra money, or will you be spending the majority, if not all, of your pay on child care, so is it financially going to be worth going back to that particular job? Or will they let you do some work from home so you don't have to worry so much about child care, or let you work school hours, so from 9-3 so you only have to worry about care for one child?

If you need to work, could you look at finding a part time/casual job where you can do night hours or on weekends when your OH will be able to look after the kids?

It's not an easy decision to make, but I think firstly if it is not going to be financially worth it, then maybe extend your maternity leave for another 12 months, at least then you are still leaving your options open.