In this guide
1. I want to change a residential building or land into a shop
The regulations define converting a home into a shop as a 'material change of use' and specify the requirements with which, as a result of that change of use, the building, or the relevant part of the building, must comply.
The specific requirements include those concerned with escape and other fire precautions, hygiene, energy conservation, and access to and use of buildings.
The building may therefore need to be upgraded to make it comply with the specified requirements.
You should also check with the local fire authority, usually the County Council, to see what 'on-going' fire precautions legislation will apply when the building is in use.