Sorry to hear about your predicament.
(1) Do contact your bank before you run into trouble with paying Direct Debits. They'll be more likely to negotiate with you if you come to them first, rather than them contacting you about missed repayments.
(2) Before you meet your bank, try to work out what level of repayment you can afford once you figure out your entitlements from the State. You're more likely to get a hearing if you're approaching the bank offering to pay something, rather than proposing that you'll simply default on your obligations altogether.
(3) If you don't pay, the bank can repossess your house, although there is a fairly lengthy legal process before that happens. If they do repossess your house and sell it for less than your mortgage, you are still liable to pay them back the difference. It will also have an effect on your credit rating and will make it difficult, if not impossible for you to get a credit card, overdraft, car loan etc., again until years after the original debt has been fully repaid.