Lamb and couscous from Claudia Roden? It is genuinely very easy yet tasty. Plus you can make it ahead of time. If you're thinking you can't cook couscous, don't worry. The technique is a doddle. It is from her book Arabesque, which is full of low effort but high impact recipes.
If that is too exotic, try something from Delia Smith because her recipes are well-tested and super-reliable. If you follow one of her recipes to the letter, it will turn out well. Also, her website has how-to videos. Her boeuf bourgignon recipe is very nice.
Also: no one needs 3 courses. Just do two. Either Starter and main, then serve chocolates with the after dinner coffee, or main and pudding. If you do pudding, remember that people generally love simple puds, most of which you can buy rather than make. A couple of extras like posh sweets or a nice brandy and your guests will feel very spoilt.
One pudding I often serve is always popular: get a large platter (e.g. what you serve the turkey on at Christmas). Pile it high with a mixture of fresh and dried fruit, the best you can find. Grapes, clementines, kiwis, mango, strawberries, prunes, dates, slices of pineapple-any combination that looks colourful. Scatter over chunks of posh chocolate, florentines, shortbreads, caramels, nougat and fruit jellies. Give everyone a small skewer or two and let them dig in.
Or, serve a good bought ice cream with home made shortbread biscuits. Again, Delia has a nice recipe. Just add some flavouring to the biscuits. Try lemon zest, or dip them in chocolate, or try dried lavender (Bart's Spices, sold in Waitrose) to be really fancy.