http://www.bbc.co.uk/news/business-40288125

The longer you can fix for, the better.

That would depend on your circumstances. If you can guarantee no change of circumstances then yes that would be good. If there is any chance you might need to get rid of the mortgage then that’s a foolish view.
Going into the greatest period of uncertainty the country has seen in recent times (Brexit and a less than stable government) can you be certain you’ll have a job for the next 5 years that will keep up with repayments? If you’re on a long fixed mortgage you may then have to hand over £10k to the bank if you sell the house.
Early repayment doesn’t just apply when you have a surplus of cash, it’s also if you sell the house for any reason. This could also include getting married and consolidating two houses down to one (aka two mortgages down to one). How about divorce when you need to split the assets?

You can get insurances against some of those risks.

Back in 2006 I took up the offer from the Abbey for a 0.49% tracker above the base rate for the life of the mortgage. Now it’s with Santander but still one of the best punts I have taken. 🙂

Obviously, Abbey was still making money on it or they wouldn’t have offered it.

In contrast we took out a 5.78% 5 year fixed term just before the crash in 2008. 😯