At the end of the fixed rate period you generally move onto the mortgage lender’s own Standard Variable Rate (SVR) – normally around 2% to 3% higher than the Bank of England Base Rate (BBR).
During a fixed rate period you are normally tied in to the mortgage with early redemption penalties payable should you wish to pay off the mortgage in part or full. After the fixed rate period you are normally free to redeem the mortgage in full without penalty, allowing you to re-mortgage if you want to.