Reading Festival 2020Watch
I went for a weekend and the music starts on Friday but most people come on Thursday so they can find a place to put their tent. I came Thursday afternoon and really struggled to find a place, we had to walk for an hour through the campsite to find somewhere. I'd def advise going on Thursday, earlier in the day if you want a good spot.
The bathrooms in the campsite are horrible, bring toilet roll but avoid them completely if possible. There are better ones in the main stage area.
The food is very expensive, it was like 8 or 9 pounds for some chips, so if you aren't bringing food, bring quite a lot of money.
Last year loads of people had those foldable garden chair circles and I really regret not bringing any cause the people that had them just straight up chilled while we had to sit in our stuffy tent.
Bring your own drinks if you aren't over 18, they ask for ID at all shops in the festival. They also had sniffer dogs at the entrance but they were pretty useless.
Good luck and have fun