Same rules apply to pretty much all venues now. Stuff your pockets with the treats and you should be fine. Bring a little reusable shopping bag or an ultralight https://www.amazon.co.uk/Sea-Summit-Ultra-Sil-Nano-Daypack/dp/B07QN5WPD9/ref=asc_df_B07QN5WPD9/?tag=googshopuk-21&linkCode=df0&hvadid=399647712860&hvpos=1o4&hvnetw=g&hvrand=3380134308134898361&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-779993499830&psc=1&tag=&ref=&adgrpid=88836927967&hvpone=&hvptwo=&hvadid=399647712860&hvpos=1o4&hvnetw=g&hvrand=3380134308134898361&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-779993499830 (rucksack) to collate the stash once in your seats.
Drinks are a no-no because some idiots have thrown full bottles in crowds. Some venues will allow plastic bottles so long as you remove the lid, but more and more are stopping this because some people are bringing spare lids.
There is generally no storage, some provide bins. You get the choice of binning the bag, or leaving. The events in Trinity during the summer allowed people to leave large bags to one side by the security checks, but it was completely at your risk, they may not be there when you return as there was no checking as to whether bags belonged to the people collecting them.