Rickman, your solicitor should write to his stating that interest will be charged for every day the money is outstanding. That might make him behave like an adult.
He really is an *rse. PR means very little in practical terms. Theoretically it gives him a say in the children's upbringing, but, if there is a dispute over, say, which school they should attend, then one parent has to make the decision and that parent is going to be the primary carer. He probably thinks it will give him some control over you and the children, but it doesn't.