For X-mas Eve, I suggest Giant catered platters, e.g.,:
http://giantfood.com/onlinestore/storeitem.html?&iid=203&cid=132&sid=350&lang=0&vid=20060501002
http://giantfood.com/onlinestore/storeitem.html?&iid=192&cid=138&sid=350&lang=0&vid=20060501002
http://giantfood.com/onlinestore/storeitem.html?&iid=342&cid=138&sid=350&lang=0&vid=20060501002
For X-mas day, Giant also sell cooked sliced hams in the refrigerated meat section. You don't need to pre-order but you may want to check a few days ahead to make sure they have them.
For appetizers:
Buy crackers, a wedge of blue cheese, a wedge of a hard cheese like cheddar or manchego, and a goat cheese (coated in chives or herbs for festive green look). Arrange on a large cutting board or platter that you can cut on with appropriate spreaders/cutters and crackers. Wash off bunches of grapes, and snip the stems with scissors to make small bunches and decorate the edges of the platter.
Buy pre-made hummus and serve with pre cut baby carrots.
Buy roasted LIGHTLY salted or no salt cashews or other nuts.
Buy PITTED olives, whatever you like. Drain and serve in a little bowl on a smaller platter with pre-sliced sliced salmi.
Slice up or buy pre sliced melon or serve a bowl of berries.
For dinner:
Ham (pre-cooked, pre-sliced) and potato rolls on platter. Can serve at room temperature.
Salad: Can you make a green salad? Consider adding pistachios, cranberries, and maybe thinly sliced endive to make it look Christmasy. You can prep the day b/f but don't put any dressing on. If you don't own a salad spinner, buy the Oxo. Well dried lettuce will wilt less.
Sweet potatoes: Do you own a rimmed, half baking sheet? If not you need to buy one and practice this recipe. It was written for kids. (Double it for the day off.) Personally I would use all sweet potatoes b/c I love them with ham.
http://www.jamieoliver.com/recipes/vegetables-recipes/smoky-mixed-potato-wedges/#SmiU2qcvMOdxPdIg.97
Frozen peas: If you can boil water you can make these:
http://www.wikihow.com/Cook-Frozen-Peas
Top with butter.
Dessert: Buy awesome pie, cupcakes, or cookies.
Day of starting about 2 hours b/f arrange appetizers, set out ham on platter. Pre heat oven. Set water onto boil. Prep ingredients and "cook." Arrange desserts on platter and leave in the kitchen.