You can have a meter wherever you like. The meter in the first house we bought, a new build, in 1969 had both meters in a cupboard outside the front door. Some people have meters in meter boxes outside.
We needed to move our electricity a few years ago and it was moved to a cupboard built into the kitchen wall outside.
The usual limitation is where your gas or electricity supply comes into the house. Our gas meter is under the stairs and we know that the gas pipe runs under our front path, which means that we could have the meter just outside the front door, but could not have it beside the electricity meter out the back as the main gas pipe doesnt run that faar.
To change your meter you need to contact your energy supplier. If that is British Gas, contact Brtish Gas, but if you are a customer of octopus, or EDF, or SSE, or any other supplier, you must contact them. Our meter was moved by SSE as they were our energy supplier at the time.