You do not necessarily need planning permission to work from home. The key test is whether the overall character of the dwelling will change as a result of the business.
If the answer to any of the following questions is 'yes', then permission will probably be needed:
Whatever business you carry out from your home, whether it involves using part of it as a bed-sit or for 'bed and breakfast' accommodation, using a room as your personal office, providing a childminding service, for hairdressing, dressmaking or music teaching, or using buildings in the garden for repairing cars or storing goods connected with a business - the key test is: is it still mainly a home or has it become business premises?
If you are in doubt you may apply to your council for a Certificate of Lawful Use for the proposed activity, to confirm it is not a change of use and still the lawful use.
The regulations do not define this particular change of use as 'material'.
However, if your proposed project involves work which will affect the structure of the building, the means of escape and other fire precautions, or affect the access to and use of buildings, the regulations will regard your work as a 'material alteration' (and therefore 'Building Work') which must then comply with the regulations.
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.
This is an introductory guide and is not a definitive source of legal information. Read the full disclaimer here.
This guidance relates to the planning regime for England. Policy in Wales may differ. If in doubt contact your Local Planning Authority.