Have you got a slow cooker? How about preparing a stew of some kind, eg coq au vin, beef - there are lots of straightforward recipes on line. The beauty of doing it in the slow cooker is that you can set it going in the morning so it will be ready early evening and it will look after itself. If you add plenty of veg to the pot then all you need to serve as a side would be mashed or boiled potatoes and maybe some peas.
If you want to have a dessert, there are plenty of delicious ready made ones from the likes of Marks, Sainsbury’s, etc to take the pressure off, or maybe make a fruit crumble - that can be prepared well in advance then popped in the oven whilst eating your main course.
Of course, a buffet will be equally as acceptable, but it does require some work putting it all together if doing it from scratch yourself, though of course supermarkets do ready prepared ones which include mini sandwiches with various fillings, mini pork pies, sausage rolls and quiche plus various other bits. I’ve used those in the past and they’ve been very acceptable - just add a few extra savouries such as crisps, nuts, cheese and crackers, etc (checking for allergies/intolerances beforehand) and a couple of sweet things., plus a variety of drinks.
Whatever you choose, relax and enjoy the company of your neighbours, so prepare something that does not require too much last minute faffing.
Out of interest, what did your neighbours provide when you went to them? Could you do something similar?