Only myself and dp here but we do different shifts so lots of times I cook for one. My dp doesnt like gravy so when I make a casarole I dish up but the remaining sause/gravy I bag up in freezer bag couple of ladles in each tie the bag and place in takeaway tub. I place the bag in the tub first so they fit.
That way if I dont have work I take four sauasges cook them pull out homemade forzen mash ( always make enough for 4 people so can freezer in either a one petson or 2 person portion ) deforst in microwave while sausages cooking and one of the fozen bags of gravy open bag place in jug deforst and heat through. Sauasges and mash with yummy gravy. And my dp has the other sausages for sauasge sarnies for breakie
I also buy 6 pint milk but seprate into pint bottles (the one pint plastic bottles that when used I wash out) and freeze the milk that way save money as one pint from shop are expenisve ( I did this when my dc used to have phasres of going off milk) The plastic bottles can used time and time again
I also freeze sliced bread and used it straight from freezer for toast ( I buy the reduced bread for this to save money)
Cook pasta for 2 people than half it so you can make a pasta salad the next day.
My dp hates ham. I got a small ham joint reduced at xmas boiled it up sliced it up when cold and portioned it out for sanires then wrapped in grease proof paper and froze.
I deforst it when i have work ( work nights so i pull it out of freezer in the morning) placing it in greaseproof paper means not having to pull about with a knife and means freezer is not full of half empty freezer boxes.
Cheese is always forzen here as we only buy it when on offer.
I also make own sausage rolls ( I use fozen pastry and reduced posh sauasges and make my own sauasage rolls large ones then freeze good for lunchs )
Also I buy frozen veg but also peppers onions and mushrooms.
Hope that helps