I am registered with the Vietnamese App Store, how do I change it to the uk store?

Instructions are contained here, Change your Apple ID country or region - Apple Support

However, to change to the UK store, you have to be physically located in the UK, have a credit card issued by a UK bank, and have a physical billing/mailing address in the UK.

Are you living in the U.K?

Do you have a resident there?

Do you have a valid U.K credit card issued by a UK bank?