I would very much doubt if the bank would agree to an Interst Only mortgage given the circumstances you have provided. However I am no expert when it comes to second guessing how the banks think, gave up a long time ago!
On a separate note, you do know by renting your property that you would be liable for CGT (if applicable) when selling the property. You'll also have to file tax returns with revenue and ensure that you have some way of dealing with tenant issues from the other side of the world. I think your bank will be more interested in the fact you are renting the property, than offering you interest only, ie it's possible they could change your mortgage rate because you are renting.