Access All Areas are a great way to see what goes on behind the scenes at a BE Event. You see most areas of a horse trials from control to scoring to start. The day will also include a cross country course walk. Most of the days are free as made possible using funding from Sport England, granted by the British Equestrian Federation to the British Eventing Charitable Foundation. Some of the larger events may be £10 (generally International competitions).
These days are good for clubs who run horse trials and would like to see how BE run their events.
https://www.britisheventing.com/training/courses/?RoleId=3