The problem with a fixed menu is that it doesn't allow you to take advantage of the weekly specials at the grocery store. You would do better to start with the grocery ads - thursday in my paper and then make up a menu for daycare/family for the coming week or even two weeks based on those ads so yes you are buying some of what you need for week two on sale the first week and then augmenting with fresh stuff which is somewhat the same week to week.

I don't worry too much about variety because the kids don't appreciate it. They like things a certain way and are quite content if chicken is always one way where an adult appreciate varying the spices and sauces a lot more. Because I serve mostly finger foods to all age groups so I don't have to make several meals to cover all the ages just having a house of basic items works for me. It might be boring to everyone else but the kids are happy and eat and my parents appreciate that more than how much I vary the menu.