Planning permission would be required for such a material change of use as the proposed new use is a different use class within the planning system.
The majority of local authorities have designated shopping or commercial areas within their planning policies where they may consider such a change of use suitable. It is likely to be very difficult to gain permission outside these areas such as in a wholly residential area.
While permission is not required before work starts, if permission is refused the work will have to be undone and the authority may take formal enforcement action over a change of use without planning permission.
You may also require the consent of the landlord or landowner.
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.
Disclaimer - Wales
This is an introductory guide and is not a definitive source of legal information. This guidance relates to the planning regime for Wales. Policy in England may differ. If in doubt contact your Local Planning Authority.