Neither is a problem, leftover cheese will just get eaten as a snack if it’s not enough to keep until I go to the shop next (I usually go every other day for something since it’s a 2 min walk)

Leftover bread just becomes a piece of toast with some butter (I basically always have it in, and get the replacement before I totally run out). Tbh with a coffee that’s just my normal breakfast some days anyway

You always have a toaster and butter on the train?
I’ve gotta be honest I somehow missed the entire context added to the body, but OP gave a good answer anyway
I screwed up the original post. It went to a nearly dead community, and I tried to fix that by cross posting it here, but I screwed up that as well. Initially, it was just a title and a picture, with no extra details. As soon as I realized that, I quickly copied the original body here as well. However, many people had already replied by then. Oh well…