To change the use of my building or site?
The Planning Portal website has information regarding the use classes order and what changes can potentially be carried out under 'permitted development'.
You are also advised to check the property history of the site, as there may be a condition which restricts the use of the building. More information about how to search planning history for a site can be found here.
Should you wish to find out whether or not you are likely to get planning permission for change of use then you should submit a pre application query. For more details about pre application queries and fees please look here.
If you know that planning permission will be required to change the use of your building or site, further guidance on making an application and information needed to register an application can be found here.
Do I need planning permission?