Wonderer
Why are you buying the house now with a view to living in it after three years?
Who is your current lender? If you sell your current home and buy the new house, you will be able to bring the tracker with you depending on the lender.
This is so valuable, that I would suggest that you don't buy a house until you are ready to move into it.
If you want this house and only this house, but can't move into it for three years, you might do a deal with a relative to buy it in their name so that you can buy it from them after three years and move your tracker.
The interest savings will outweigh the 1% stamp duty and 2% legal fees. There could be a CGT bill but you will have that anyway.
Brendan