Not a med student yet but as an offer holder I guess my response is fine as well.
Your experience at the food drive is valuable and you should definitely mention it. It's perhaps not quite enough though. Med schools want to see long-term volunteering in a healthcare environment (care home, hospital etc) where you've played an active role in helping patients. You might also want to get a hospital shadowing placement but that's not essential. Personally I volunteered at a care home for about a year and a hospital for about six months.
Whatever you end up doing in terms of work experience, the most important thing is to reflect well on what you've seen. Highlight what you learned about the realities of working as a doctor and give examples of situations where you've shown important characteristics like empathy.
Could go on about books for hours lol. Here are some I enjoyed:
General stuff on being a doctor:
When breath becomes air - Kalanithi
Being mortal, Complications and The checklist manifesto - Gawande
Gratitude, The man who mistook his wife for a hat - Sacks
Trust me, I'm a junior doctor - Pemberton
Do no harm - Marsh
Medical-ish sciencey stuff:
Bad science, I think you'll find it's a bit more complicated than that - Goldacre
I contain multitudes - Yong
Phantoms in the brain - Ramachandran
This is your brain on parasites - McAuliffe
The selfish gene - Dawkins
The music of life - Noble
(The last two make an interesting read together.)
Can also recommed quite a few psych related books if you're into that sort of thing but will not list them here now in case you're not.
A very short introduction to medical ethics is a useful little book to read before your interviews.
I got a pretty good UKCAT. I used the ISC 1000Q book (can recommend, although you maybe should get the new 1250Q edition) and the Medic Portal question bank (can't recommend tbh, maybe get Medify instead) plus the mocks on the official UKCAT website.