Step 4:
Look into the amount of tax credit which should now be paid on a single-person basis:
http://www.hmrc.gov.uk/taxcredits/
Step 5:
Consider whether there's any realistic chance of actually being able to keep up the mortgage repayments. (I suspect that the answer to that will be 'No'). If it looks like the house will be repossessed, see here for valuable information:
http://england.shelte...k/get_advice/eviction
Step 6:
Thinking ahead, look into Local Housing Allowance for private renting:
http://www.direct.gov.../DoItOnline/DG_196239
(See also the relevant pages from the Shelter website, as above)
Step 7 (or possibly Step 0, right at the beginning):
Contact the local CAB, for further advice:
http://www.citizensadvice.org.uk/getadvice.htm
(See the bottom of that page to find the nearest office).
Finally (at the risk of sounding like Corporal Jones, from Dad's Army):
DON'T PANIC!
Simply stop paying (or seek reduced payments for) any bills which aren't IMMEDIATELY vital. Concentrate on the important things, putting food at the very top of the list.
Chris