Class E of The Town and Country Planning (General Permitted Development) (England) Order 2015 permits the erection of buildings, enclosures, pools and containers subject to limitations and conditions.
In addition to complying with the limitations, the condition is that it needs to be used incidental to the main house. Here is a list of some examples:
- Shed
- Office
- Garage
- Greenhouse
- Gym
- Store room
- Swimming pool
- Kennels
Please refer to this legislation.