pay back the money as fast as posable
Purely out of interest, how common is it to have your mortgage split into multiple tranches? Ours is in three fixed portions, plus a small floating overdraft. Each time one comes up, we re-fix for 3 years - so each year we have one portion coming up for renewal. Gives us a good bit of insulation against drastic changes in the rates, as any change can only affect 1/3 of your total monthly repayment.