Occasional Use Notices (OUNs)
Occasional use notices allow a licensed betting business to provide betting facilities at a sporting venue for short periods of time without the need for a full betting premises licence.
The event must be temporary or infrequent. OUNs may not be used for more than eight days in a calendar year in respect of any one venue.
You can get them from your local licensing authority.
Section 39 of the Gambling Act 2005
An occasional use notice must be sent in writing to your local licensing authority in advance of the event and be copied to the chief officer of police for the area in which the venue is located (or, in Scotland, the chief constable of the police force for the area).
The person administering the gambling under an OUN must have a Gambling Commission operating licence (that is, must be a licensed bookmaker).