Hi
I went abroad last year for work, and I got a moratorium on my mortgage for 3 months. There were no specific conditions/penalties attached to this, but obviously since I wasn't paying the mortgage, the interest would have increased during that period, and of course, the capital stayed static. Whether you extend the term, or accrue interest, you will end up paying either way, I suspect. And I can't imagine that the bank would freeze interest.
The only forms I filled in were to confirm the months I would be taking a mortgage break for. I just asked the bank, and there was no problem with arranging it.
I'm not sure what the situation is for longer periods of time however,
Hope this is of some help,
Best of luck tomorrow, hope it goes well for you both!
nicola