Old mobile phone contracts can be linked to old addresses and if they are listed as open, this can disrupt applications due to ID checks listing different addresses for you.

You can find this information out by checking your file. It's worth doing so because the impact of wrong addresses might derail an application for a mortgage, for example.

With a fixed rate mortgage, the interest rate remains the same during the period of the fix, which could be 2, 3, 5 or even 10 years, after which it reverts to the lender's standard variable rate, which can move up and down.

Although you might be paying a higher rate initially with a fixed rate, it is predictable in terms of the required repayment and you are cushioned against the lender's costs of borrowing increasing (such as because, for example, the Bank of England has raised its base interest rate). You are locked in, however, and you cannot leave early without having to pay a large repayment charge. Once the fixed period has finished, you are free to organise a further fixed term (and fixed interest rate) with your lender or to change lenders and take up another mortgage entirely, which might, for example, be another fixed term mortgage.