There only two important contact details on a United Kingdom passport are date of birth and name. It is important that people who are recently married, divorced or adopted change the name on their UK passport. If a person's legal name does not match the name on their UK passport, international travel is prohibited.
Download the Passports for Newlyweds and Civil Partners leaflet and form from the UK Identity and Passport service (IPS). The form and leaflet also can be obtained by calling the IPS and having them mail a form to you or by visiting any Post Office with a "Check and Send" service.
Fill out the appropriate sections as instructed on the form. If you are already married, enclose a copy of your marriage certificate. If you are waiting to get married, the officiant must sign the 'Passports for Newly Weds and Civil Partners' form too. The earliest you can change the name on your UK passport is 12 weeks prior to your wedding.
Enclose the fee for changing your name and mail the "Passports for Newlyweds and Civil Partners" form and supporting documentation to the IPS. Fees for changing the contact details on a UK passport vary, depending on how quickly you need the changes to be made. Premium one-day, one-week fast track and standard services are available.
Visit your nearest post office "Check and Send" service if you want to change the name on your passport for any reason other than marriage. This can be done in person, without the signature of anyone else required.
Provide any official documentation that relates to the name change. This might include a birth certificate, divorce decree, deed poll or a letter from your doctor, should you be changing your name as a result of gender transformation.
Pay the necessary fees in person at the post office. Fees vary with mailing time. Standard service is the cheapest.
Plan well in advance for name changes as a result of marriage. You don't want to be stuck at the airport on your honeymoon because you forgot to change the contact details on your UK passport.
Any visas in your current UK passport may be invalidated when you change your name. Speak to the IPS to find out if visas can be carried over to your new passport.