If you wish to move where the Gas Meter is located then you can ask the Gas Transporter for your local Gas Network, for a Gas Alteration. You can fill in form on thier website, to get a quote. If you are wishing to move it to allow you to turn the gas off at the Emergancy Control Valve, then clear give this as reason. They will send a surveyor to discuss the access to the ECV for given cicumstances, and best way to change location to allow.