@JayPee that's really helpful, thank you. I'd already included some of your bulletpoints in my draft. I'm a team leader in local Government for work and have been involved in a mental health charity for 10 years, so skills I have associated with those roles are what I'm putting down.
I've been reading some positive experiences from people volunteering on here, so going forward I would look into continuing volunteering with Water aid in the future not just for one festival.