I would probably say remortgage if you can, if not, sell and move to a smaller house. I think an IVA would completely obliterate your credit rating. As you have other options available to you, its probably better for the long term for you to try the other options first.

It may be worth getting an appointment with your local CAB and also arrange an appointment with a local independent mortgage adviser who will be able to go through your mortgage options with you.

Whatever you do, you've taken the hardest first step - admitting you have a problem. I'm sure there will be a solution available to you - best of luck and let us know how you get on :)