The Event Organiser shall ensure that they provide sufficient first aid cover for the number of people attending the event.
The recommended minimum number of first aiders at small events where there are no special risks considered likely is 2:1000 for the first 3,000 attending.
No event should have less than 2 first aiders.
A Medical plan will be required as part of your event application this should give the detail of provision during your event as well as your build and break period.
See HSE GuidanceAll event guidance