There is no right length (term) to a mortgage. The standard term is around 25 years, and most of us tend to have a mortgage throughout our working lifetime. With the large sums involved, this spreads the cost and makes your monthly payments more manageable.
However, you can choose a different term if it suits you and the lender agrees that you can afford it. If you can afford a shorter term you may have higher monthly payments but pay less in total (see table below). With a longer term, you may pay less each month but more in total.
Ask for ‘Key facts about this mortgage’ documents showing different mortgage terms and use Section 5 to compare the total cost of a mortgage over different terms. Try not to make financial commitments that go past the age you retire unless you're sure you'll be able to afford the payments.
Example of how the term alters the cost of a repayment mortgage if interest is 6% a year.

In Summary
1. Remember that a mortgage should fit comfortably with your earnings and your commitments.
2. Don't take out a mortgage that runs past your retirement, if you're not certain you will be able to afford it.