Hi llw and welcome to the forum
You have substantial equity in your property, and could re-mortgage on a self-certified basis so long as you could afford the repayments. You would need to seek specialist mortgage advice on this point.
As you can afford £425 per month, it will definately be possible for you to propose an IVA, and the actual structure of this will be discussed with you by the insolvency practitioner you choose to represent you. I suggest that you approach a suitable professional, who can give you more specific advice about your current situation and options, before you are tempted to borrow any more money. And avoid secured loans like the plague if you can help it.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk