If you intend to work from home you will require planning permission to do so if the overall character of your house changes from the primary and predominant use as a dwelling house. Instances where this would occur include a use that attracts a marked rise in traffic or people calling, a use that involves activities unusual in a residential area or a use that could disturb your neighbours.
However, many businesses can exist invisibly within houses or in outbuildings in the garden without any formal change of use occurring in planning terms. More information on working from home is provided in the Department of Communities and Local Government booklet;