Don’t faff too much with the trimmings. Bit of simple greens is fine. Roast potatoes are just chopped potatoes ina n oven with some oil, maybe salt and rosemary but no biggie*. Not averse to your cauliflower cheese wildcards and such. Put your effort into the gravy.
*About 10-15 years ago there was a spate of people going batshit crazy for roast potatoes recipes. Coating them in semolina, bashing them about in a pot before roasting them, cutting at particular angles etc ad infinitum. Theyre very easy to make stop overdoing it.