Well, at least it's a positive situation.
The trouble is it really comes down to what you want and expect - the trouble with interest rates is that banks have stopped tracking the Bank of England rate and now have Mortgage Standard Rates (or similar) which is their own tracker set up the BoE's rate.
So it really would be a case of just doing the maths and seeing what would work out best for you. If there's little call between either option, then it sounds like the repayment period may be so small that neither makes a significant difference.
Hope that helps.