I'm no legal expert but I think under English Law your assets would be at risk due to your married status. I would suggest you seek legal advice on this. So far from what you say your husband has refused to acknowledge the debt. I hope that he is also following the excellent advice on this site about putting the lender to strict proof of claim.(posted 7991 days ago)If I were in your shoes I would close my account with your lender and open another one elsewhere. Even though they probably already know what you earn / spend in round terms there's no point making it easier for them is there?
As to the question of settling with them, you should first try to see how their claim is made up. If your mortgage predates 1989 and you had a MIG policy which was redeemed by the lender, then a portion of their claim may already be statute barred, although as you will see by looking at recent postings, this has yet to be definitively judged to be the case.
It sounds from what you tell us of your circumstances that you would be able to settle for a reduced amount, but the trick is how to achieve a realistic settlement with lenders who tend to continue to ask for I&E forms to be completed.