The mortgage rate for tracker mortgage is usually a bit higher than the base rate of the Bank of England. However, the tracker's rate mirrors the one from the Bank, meaning that if the latter goes up or down, so will the tracker's one. The two basic advantages to the tracker mortgage are that you will certainly benefit from a Bank of England's reduction and that you will pay a low interest rate during the first years. Still, the mortgage rate for tracker mortgage can present some difficulties.
For example, should the Bank's rate go up, your mortgage rate for tracker mortgage will also increase accordingly. In short, an increased mortgage rate for tracker mortgage will result in your paying a lot more than you should.