You best bet would be to talk to one of the brokers, as they will know which institutions would be likely to take your mortgage & which ones wouldn't. If you're going to move your mortgage don't forget about the legal fees, valutation fees & a bit of hassle.
I have looked into doing something similar myself, but as I can't take a career break (no guarantee of job on my return) lenders are reluctant. Also, you could go interest only for the year, reducing your repayments & rent your property out, thus paying off a smaller mortgage & giving you some income while you are away.
I spoke to rea mortgages if that's any good to you.
Good luck. MH