You can take one folding chair per person - there’s a dedicated seating area for those who wish to sit down.
It’s best to dress for the British weather, bearing in mind you’ll be standing and the concert area is on grass.
Small umbrellas are allowed, but any large parasols or golf sized umbrellas won’t be.
You can take soft drinks, but they must be in a 500ml sealed plastic bottle. Food or alcoholic drinks can't be taken inside the fenced concert arena, but there'll be plenty of places for you to get something to eat.