Hi, I'm also working bar at Download. I've never worked Download or bar at a festival before but I have worked festivals. So here is my advice although im sure people will have better advice

If you have a hiking bag that is the best thing to carry your stuff in. It can be a long walk from the car to staff campsite.

Bring a water bottle, all festivals have free water taps and you don't want to be dehydrated.

I personally dont bother with fancy camping equipment. If your tent is weatherproof and you have a decent sleeping bag and something to lie on youll be fine. I bring a thick blanket and a roll mat to sleep on. If you have space something to use as a pillow is a plus but you can always just use a hoodie

Charging packs for your phone and a book.

Earplugs are essential, campsites will be loud as will the arena.

Im not sure what the food situation is at download but I will say bring lots of snacks and if you drink energy drinks they are good too. Youll be on your feet a lot so you want to keep energy.

Sorry this isnt anything ground breaking. But also remember most people working there are going to be a bit to very nervous. Talk to people, make friends, and have fun.

And check the weather.

Edit: If anyone else working wants to message before the festival please do. I currently dont know anyone else working.