You don't need to have a wedding to update your passport, though. The UK Government is also issuing a warning to others. It says that people will need to get a new passport to travel abroad or prove their identity if they change their names, including their first.
You will also need to get a new travel document if you change your gender or appearance. Whilst hair dye or glasses are not included, the document explains that the only time you need to update it is if you "cannot be recognised from your passport photo any more, for example, you’ve had plastic surgery."
You do not need to get a new passport if you:
You can find out long it will take to get your passport before submitting your application. If you need it in a hurry, don’t worry as their Online Premium or 1 week Fast Track services are available for urgent cases. Just remember, do not book any travel until you have your new passport in hand, as it will have a different number from your old one.