Permissions and regulations
The two main permissions you will most often require for building work are Planning Permission and Building Regulations consent.
Planning Permission deals with the overall issue of what kind of houses are permissible in which area. The planning officers are employed by the local council.
Building Regulations deal with whether the building is built properly and is safe and energy efficient etc. The building inspectors are either employed by the local council or are private companies approved to do the work. You can choose which you want to use. It is normal to get planning permission before building regs approval because if there is a problem with planning permissionthen it might affect the building regs drawings, although an architect will tend to develop both at the same time.
It is quite likely that if you are employing an architect or building consultant or someone else to do your drawings and design work that they will handle the drawing and form-filling necessary to obtain planning permission and building regulation consent. However it is useful to have an understanding of what is going on.
See the government Planning Portal site which deals with both Planning consent and Building Regulations.
The regulations regarding outbuildings such as garden sheds are often contained in local council bye-laws rather than being part of the national Building Regulations or planning consent so it is worth checking these out early in the design process. Contact the local council to find out more