I agree that you need professional advice on this. And I think KBC is covered by the David Hall organisation, for free, look up their website.
If your wife's income is very low, then it's highly unlikely the bank will be able to get anything from her. Yes she will still owe the debt, but they will need to get her to agree to repay it, or else they will have to go get an instalment order.
I pressume she doesn't own the house you life in?
PPR
It is not her PPR anymore. Obviously there is no tax gain, so she will not be liable for CGT, but I think she may be obliged to fill out a return nevertheless, and it's in her interest in any case, because she will have a loss, she can carry it forward against any future gains.