Clubs in the YHOA region put on a large number of events and activities throughout the year. The best way to find them is via the British Orienteering website, which has an interactive page where you can select region, dates, distance from home and more.
Events are graded from Level A (National) to Level D (Local). The first link below opens the British Orienteering list filtered for YHOA events. The second lists club activities such as training, club nights and so on.