I think no one will fault you at all for being not entirely prepared for this particular trip! (((hugs)))
As for packing snacks, I usually do bring at least some with me. I dislike having to leave my room for breakfast if I don't need to, plus liking to have something available if I don't want to interrupt what I'm doing in order to grab food. Plus, an easy way to save a few bucks.
And having never been on any cruises, it's all new to me! I don't think I'm really a cruise person. Of all the options, I'm probably most likely to someday do an Alaska cruise of some sort, since it seems like by far the simplest way to visit there.