Once you have identified your preferred site for your event to be held, it is essential to gain permission from the land owner. Broadly, land ownership falls into two groups: Public and Private.
Publicly owned land
Publicly owned land is primarily controlled through various Local Authority departments. To use an outdoor space such as a park or common, the Parks and Green Spaces Department (titles vary) of the relevant Local Authority should be contacted for advice. Buildings owned by the Local Authority may come under the authority of a number of departments, requiring further investigation. It should be noted that there may be restrictions on the use of some Local Authority owned property. Depending upon the nature of your event a ground rent may be payable for use of public land. Please refer to the relevant Local Authority websites for further information and contact details.
Privately owned land
To hold an event on privately owned land, you must identify the owner of the land and approach them or their agent directly, then negotiate terms as a private contract. In some instances identifying the owner of land or a property may be difficult, however resources such as the Land Registry can be of use: http://www.landregistry.gov.uk/