Who Pays For Nursery/Childcare Costs After Divorce?

We all know how expensive childcare and nursery costs can be when you are a couple, but the situation can be exacerbated if your relationship breaks down. Ideally, it is best to sort out childcare or nursery costs with your ex as soon as you separate if you are to minimise disruption on the child. And this includes resolving things like who pays, and whether such expenses are part of child maintenance payments?