What makes you think he is going to declare himself bankrupt?
If I was paying half a mortgage, giving 20% of my salary towards my children and paying rent/bills on another house, I would have no money left for the month either!
Anyway, after a quick search, I looks like the house might have to be sold:
What are the effects of Bankruptcy?
Once you have been made bankrupt all assets belonging to you come under the control of the Trustee, including your home.
Where the home is co-owned, the debtor’s interest can still be realised, but a right of occupation period of twelve months is allowed for the disposal of the property if a co-owner, family or dependents of the debtor occupy it. At the end of the twelve-month period, the property will almost certainly have to be put up for sale, enforced by a Court order if necessary.



