I second Leclused and Pete's suggestions.
In my opinion it's important to carry a knife on SRT trips, even if it's only used for slicing cheese. I hope never to have to use it but even for cutting hair/beard out of a descender it could save you a lot of pain and faff as long as you could see what you were doing
Sometimes I carry a dangly bag (small personal tackle sack) on my belt, and sometimes I don't. It depends if there's room in other tacklesacks, in which case I'll put things in those, or if I think a small bag will really get in the way.
If I'm taking my dangly bag I'll stuff most things in there. Otherwise, I'll shove them in my oversuit & undersuit pockets and down the front of my suits. I wear a belt so this works even if I'm not wearing my harness.
I carry some things on cord round my neck (spare light, knife, whistle).
Not everyone chooses to carry a first aid kit, so if that's something you're keen on and no-one else is carrying one, I would put something small together inside a waterproof container or a tough drybag and either carry that in a dangly bag or find space for it in one of the big tackle sacks.
A friend carries a puffy jacket in a very thin dry bag, which is inside a tough dry bag, which he carries in a dangly bag. But a personal survival bag is a good call. It's a shame those thin clear ones are not so easy to get now - they fit into an oversuit pocket and were really good when you needed them.
In terms of food - definitely take something you do like! It's more than just calories. And don't be afraid to eat it. I eat much more these days on caving trips than I used to - it has taken me years to get round to that way of thinking, but I run out of "go" otherwise.
Please let us know how you get on