The short answer to your divorce proceedings:
Unfortunately, you can not do this unless you got the permission from the mother of your children while you are in the middle of divorcing.
The long requirement by family law
If you take the children out of Australia without permission from the other parents, or there are court proceedings, you could be committing a criminal offense regardless whether any court orders are in place.
Please bear in mind, both parents of children have natural custody until an agreement has been reached or endorsed by Court.