Traveller’s cheques are more like banker’s drafts than traditional British cheques because they contain the value of their face value. That is, a cheque presents the payee with the right to take an amount of money out of your account, but you have to take money out of your account to buy traveller’s cheques, meaning that they have that value immediately.
American Express advises that their traveller’s cheques never expire, so just keep your unused cheques for your next trip. However, if you want to cash them in, you have a number of alternatives.
Take your traveller’s cheques to your bank and pay them into your account. The bank will credit your account immediately and sort out collecting the money from the issuer. This is particularly your best option if you bought your traveller's cheques from your bank.
Cash your traveller's cheques at the Post Office. The Post Office issues American Express traveller’s cheques, and they promise to buy those back. However, the Post Office is one of many outlets that will accept traveller’s Cheques and exchanging them for cash would be treated as a foreign exchange transaction.
Spend them. Many UK retailers accept travellers cheques as cash. Large chains, like Marks and Spencer and Debenhams, are used to accepting traveller’s cheques from foreign shoppers and they would be willing to accept them from you. This strategy is only likely to work if your traveller’s cheques are denominated in sterling.
Return the traveller’s cheques to the issuer. You may have bought the traveller’s cheques from a bank other than your own. HSBC, for example, is happy to buy back any unused traveller’s cheques you bought from them.