Aiming to be mortgage free

sgc21

Hi,
So I have a plan to be mortgage free in 4 years but thought I'd put my plan out there for comments just in case I'm missing a trick.

Mortgage debt 67k over 11yr term, currently on a 5 year fixed at 4.5% until May 2028, current payment £639 per month.

Plan to pay the maximum overpayment of 10% of mortgage balance at the start of each year without being charged a penalty for overpaying and put any extra spare funds into a savings account.

At the end of the 4th year I should hopefully have enough in the savings account to pay of the balance taking into account the 10% on the balance.

Just wanted a sanity check that this is the best option (or only option) to pay off a fixed rate mortgage early.