Fix for 2yr or 5yr terms?

Hi,

I'm about to remortgage and the 2 options I have are : -
1) 2yr fixed @ 2.79% changing to 3.94% var
2) 5yr fixed @ 3.49% changing to 3.94 var

I'm assuming BOE rates won't go up by more than 1% in the next 2 years in which case the 2 options will be roughly equal (assuming I will then remortgage at the same fixed rate). Therefore I am inclined to fix for 2 yrs.

Am I on the right train of thought?

thanks

Rob