Early Repayment Fees In Variable Rate Mortgage

I am very shortly due to begin my first step on the way to becoming Mortgage Free.

I have looked into Making an Additional Payments under the 10% Penalty Free which is fine

But it might be that i could wait until next October, when my Fixed Rate Term Ends and I would like to have an idea what the banks usually offer in terms of Early Payment Fees when not on a Fixed Rate Plan, is is usually a similar fee anyway, less or more?

Another option would be for me at the time to remortgage to borrow less, but again i'm not sure if i can do this without paying an Early Repayment fee.

If the Early Repayment Fees are indeed based on a percentage, making overpayments now in readiness for Oct 2019 would that mean it would reduce the fee i would pay if i choose to do that and see it as the best option from an informed decision.

I am with the Halifax