Don't agree to pay for the schooling. Tell her that you'd be prepared to try to make some contributions, however, not while she isn't playing nice with the orders.
Sadly, the only way to get the orders enforced is to go back to court. Even then she can continue to breach them. Mate, the system is broke. No one will ever go knock on her door and collect the kid. Not until you reach a point where a magistrate orders it and that could take years. Most kids grow up before that happens or the non-primary parent gives up.
But since you're on a disability payment, contact legal aid. They might help.
As for the school fees, I very much doubt that the child support agency will make you pay half... I'd suggest you tell her that given she has shown no regard for your role in your kid's life you feel it a bit rich to expect you to pay a cent when she won't even let you see the kid. (but probably best if you ignore my help on that one...