Retrochic, bear in mind I know nada about divorce. She is probably going to be looking at obtaining an occupation order - ie an order from the Court that she occupies the former matrimonial home with the child and he moves out. He has the means to do so, she does not.
There are a couple of websites which are quite good on this type of thing. One is wikivorce and one is a site run by a lawyer called Marilyn Stowe (NB I dont know her I ought to point out, I have just used the site when dealing with a personal issue).