Sorry, I think you are utterly crazy giving up a 1.25% tracker. Fixed rates are going nowhere for the moment. Ukraine probably elongates that. Remember the media love to scaremonger people.
If you added €100 extra to your mortgage payment, then in 5 years time the balance would be under €130,000.
If interest rates rose to 2%, giving you a 3.25% rate, payments then would be €920 / month.
Push yourselves and add €150 per month immediately to the tracker mortgage payment and watch the years fall off the end date of the mortgage. Your 20 years would become just over 16 years.
But don't give up a tracker.