How long can I stay on a Marriage Visitor visa, and can I extend it?

The Marriage Visitor visa allows a single visit of up to 6 months, within which you must marry or register your civil partnership.

It cannot be extended, and you cannot switch from it to another visa category while you are in the UK. If you want to remain in the UK with your new spouse or partner after the ceremony, you would normally need to leave and apply for the appropriate partner or family visa from outside the UK.