If I'm reading this right, you're planning on picking up sandwich ingredients, etc. on the way to MCO, so you can picnic at MCO and ATL? If so, you need to re-think a bit; an airport is just NOT a good place to picnic out of whole packages and jars, partly because you need utensils for that, but mostly because carrying all that stuff through security will use up all of your carryon baggage allowance.
Packing cold meals for a flight isn't impossible, we do it all the time. However, you don't want to get the food on the WAY to the airport unless you are picking up pre-made deli sandwiches from someplace like Subway. Sandwiches are available at more-or-less street prices in the MCO food court, but I personally don't like to count on having time to buy food IN an airport when I still have security ahead of me.
If you are going to make the sandwiches/salads yourself, you need to do it at your hotel before you leave for the airport, and then pack them in individual portions in a small carry-on rolling cooler or two for transport. For condiments and spices, I recommend collecting little individual packets from food courts for a while before your trip and taking them along; jars are NOT travel-friendly. Buy a big pack of ziplocs and plan to package the lettuce, tomato, etc. separately so the bread won't get soggy. If you want chips, etc., you'll want to go with things like Pringles that are compact and protected from breakage. Each person can then take a premade sandwich packet and add whatever extras he/she likes. (BTW, If you want turkey, stick with smoked; roast turkey spoils super quickly.)
Updated: I just realized that you are coming straight off a cruise ship. If there is time before your airport transfer leaves from the port, I would try to pick up pre-ordered food in Canaveral. There is apparently a Publix quite near the port; could you have an order picked up there before going back to MCO?