We are only 3 as well, as DD is not a fan of roasts, we only do them occasionally (and Christmas is one she is happy to eat). We do a lot of the prep, together as a family, on Christmas Eve afternoon (and DD is baking her cookies for Santa at the same time - I learned many years ago to have a safety net of baking a batch of cookies in early December and freezing half the dough, so can "slice and bake" if we are short of time or energy - or she can do them from scratch if she wants and its suitable on the day).
However, another favourite meal that we do on Christmas Eve is "Platter". Basically, it involves opening a lot of packets and tubs from M&S, local deli etc, having peeled an extra few carrots to make carrot sticks for dipping, getting the Christmas cheeses laid out, and making sure that my selection has included at least 1 favourite for every person. The final selection differs depending on what we can find and also how tastes change over the years, but there is enough to enjoy without going overboard. Mostly cold but sometimes a few hot things. Things like:
Cooked and cured meats (ham, parma ham, salamis, braseola, spiced beef ….)
Fish - smoked salmon, prawns (and marie rose sauce), squid rings, garlic mussels...
Salad - nice lettuce, carrot sticks, pepper sticks, cherry tomatoes, olives, spring onions...
Flat breads or bread sticks, nice crackers for cheese, possibly nice crusty bread
Dips - hummus, marie rose, pesto, salsa...
Pork pies, sausage rolls, scotch eggs
M&S party food from the oven
Cheese board has about 5/6 cheeses usually, at least 2 hard, 1 soft and 1 blue, and usually some grapes on the side
You can change it up to suit your tastes, and numbers. Most of it will keep to eat another day if you don't finish it all. And everyone just picks what they would like from the middle of the table.