Hi there,
I'm afraid this isn't a simple answer and the best advice is to speak to an indpendent
mortgage broker. You need to way up the costs of tmoving compared to the savings involved, and then incorporate the added savings of considerable overpayments, and work out how much quicker you would need to clear the mortgage in order to make remortgaging financially beneficial.
You also need to talk through the other benefits of changing rate and weigh up the risks of having a tracker product too. So I'm afraid I can't give you an answer without a much more detailed chat about your current circumstances.