Well, being that it's summer, you could do something as simple as sandwiches (make-your-own) with individual bags of chips and fresh summer fruits (watermelon, canteloupe, etc.), and pre-wrapped snack cakes or other little desserts that are easily made or bought, like two-bite brownies. Invite people to bring something to contribute and help you if they feel led.
Hot dogs/hamburgers, cole slaw, baked beans, and chips are always a favorite. Enlist some guys who love to grill.
If you have people who have gardens, they will probably have a surplus of home-grown goodies soon. Have a veggie night and get contributions of fresh garden goods from people.
In the fall/winter months, soup and cornbread is hearty, warm, and filling. Chili, soupbeans, oyster stew, spaghetti, lasagna with fixins are great too. Around New Year's, you can have blackeyed peas, collard greens, ham, and cornbread (a New Year's tradition in the South). Beef stew and shepherd's pie are also great in the wintertime. Any of these things can be Crock-Potted ahead of time and the smell of them as one comes into the Fellowship Hall will have mouths watering.
We have several guys who do the cooking on Wednesday nights. They love to cook and to grill (what guy doesn't?), and they cook things like fried chicken and pork chops, and they are excellent biscuit makers as well. See if some of the men in your church would like to help you out. Sometimes guys love to show off their cooking skills too, but they don't always have the chance, as cooking is largely left to the womenfolk.
If you're concerned about how much time it would take to make some of these things, you can always pre-make/pre-cook some things, like biscuits (which can be frozen), and ground beef (which can be pre-browned and frozen).
Sometimes, for large church events (like our Fifth Sunday dinners), we buy food items from local businesses to supplement what we make. We get chicken tenders and Zak Sauce from Zaxby's, cole slaw, baked beans, and barbecue from a local barbecue joint. These are easy to re-heat if needed, and often come in their own large aluminum containers.
Taco casserole is always an easy make, although you'd have to multiply the ground beef/taco seasoning mix, but all you do is put a layer of tortilla chips in the bottom of a casserole dish (imagine one of those large aluminum pans, though), put a layer of seasoned taco meat on top of that, and then a layer of shredded cheese. Keep layering until the dish is full -- chips, meat, cheese -- and end off with the layer of cheese at the top. Bake it at 350 or so until the cheese is melted, serve with a salad.
Macaroni and cheese (depending on the recipe) can be easy, too.
If your church doesn't mind you taking a shortcut now and then, you could sometimes order pizzas and breadsticks, and make a salad to go with.
"Oir is leatsa an rioghachd, agus an cumhachd, agus a gloir, gu siorraidh, Amen." ("For Thine is the kingdom, and the power, and the glory, forever, Amen" -- Scots Gaelic)