Please reassure your friend that she didn't waste her time by involving the police as it seems that, including this latest incident, he's avoided being bought to account in law 3 times and his luck won't hold - sooner or later he'll encounter a copper who's prepared to go the extra distance to nail the twunt.
However, we certainly don't want your friend suffering any more upset or visible/serious injury at his hands and, to this end, I hope she realises that she has no alternative but to end this relationship and take steps to secure her position with regard to any property they own in common.
Encourage her to keep trying the WA national helpline over the weekend, or take a couple of days to recover from the shock of being attacked in her own home by the father of her dc and get on to her local WA first thing on Monday morning.
There is much that can be done to enable her and the dc to live in safety. WA can refer her to a solciitor with a view to obtaining occupation and non-molestation Orders that will enable her to remain in her jointly owned home without fear until such time as it is a sold or a longer term solution is negotiated.
If she is entertaining any hope that the relationship can continue or be resumed at some future date, she should make it conditional on him attending a Respect or similar dv offenders course but she should be prepared to live apart from him until such time as he has completed any such course and she has had feedback on his progress.
Praise the lord that she has a friend in you, squeaky, as I have no doubt that you'll do everything in your power to give her the support and encouragement she should have received from the appropriate authorities/agencies.
Although he hasn't been charged on this occasion, it may be an idea for your friend to make contact with her police authority's domestic violence unit to see what provision they can make for her or what help they can give her to break free of his violent behaviour - if she calls this unit, tell her to ask to be referred to a dv counsellor.
It's unlikely that anything productive will come from the direction of SS unless it can be proved that his behaviour is negatively impacting on the dc but, on this occasion, I doubt that she'll hear from them - and certainly not in the next few days which, of course, is the critical time that she needs the most support to strengthen her resolve.