Are you referring to trying to get a new fixed rate? If so, that will depend upon your mortgage company. You can but try.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
I would have a chat with your mortgage company now to see what options there are available to you when the current deal expires. This will not stop you getting an IVA, but it would change the figures, depending upon whether you are in a fixed term mortgage now and what the standard variable rate of your lender is.
It may also be sensible to also be chatting to an insolvency practitioner at the same time, who can give advice on all of the available debt options as well.