Is frozen pizza considered cooking on vacation? We usually do pick up a frozen pizza or two. I think some of the frozen pizzas are just as good as the pizza delivery, and you don't have to wait as long. We often don't take the time for dinner if we had a big lunch somewhere and the munchies set in at about park closing time. I pick up lunch meat, bread, chips, etc and on a sleep late day have sandwiches in the room before we take off for the parks. I also pick up a 4-roll package of toilet paper. We always seem to run out when it's not convenient to find housekeeping for more. We buy breakfast groceries for most every day, we'll usually plan one character breakfast as a brunch. My family really enjoys the Pillsbury frozen biscuits for breakfast. Which means I also have to get butter & jelly. We don't do cereal at WDW. Too much is wasted. We eat biscuits & jelly, Pop Tarts, fruit, bagels, toast, breakfast bars, powdered sugar donuts (yuk! but hey, it's vacation!) Everything mentioned above I buy in FL during our grocery stop.
From home, I bring coffee in filter packets, dry detergent in a tupperware container, dryer sheets, my favorite tea bags, medications and cold remedies, soap, shampoo, bubble bath (in small leak proof travel bottles), film, batteries.
Have fun!