2 year means paying the product fee 3 times to get to 5 years. That's somewhere from £3k-6k depending on the specific mortgage fee. Add in the hassle of looking for a new mortgage 3 times and I'd stick with 5.
At that point we should be well into a labour government with its sensible pants on.
Gah, 2 or 5 year? I know nothing. Rates are the same