As well as frozen prawns, Sainsbury's (and probably some of the others too) do bags of very small frozen scallops from Patagonia and they are also handy. They defrost in about an hour on a metal tray, and then I pan-fry them with/without prawns and add to pasta or noodles or risotto with appropriate veg.
I always have portioned-up homemade pasta sauce in the freezer - as soon as it's running low I make another big batch. Onions, garlic, celery, grated carrot, finely chopped or shredded courgette, dried mushrooms (add the soaking water as well as some stock), tinned tomatoes, anchovies and a good dollop of pesto. It's a bit of a faff to make but if you have a stockpot or big saucepan you can make 8 or more portions. I buy fresh linguine or tagliatelle to go with it as it cooks so quickly
I make a Greek spinach & filo pastry pie because that is very nice cold or room temperature & I don't seem to go off it as I do with some dishes.
Also love Greek salad - ripe tomatoes, cucumber, black olives, feta cheese, with a bit of red or spring onion (optional). And mozzarella, tomato and avocado salad with pesto mixed with vinaigrette or lemon juice.
I make soup and freeze that in individual portions too, and have it with toast or bread. Stir in some sour cream to make it more luxurious.
I keep frozen cooked portions of mushrooms, spinach and courgettes in the freezer, along with a bag of grated cheese (I buy a big block of extra mature cheddar and grate it myself, ditto Parmesan) so I can always make e.g. an omelette or a fish dish that has some veg in it.
Frozen onions and frozen parsley are absolutely brilliant. Onions mean you can start something off without chopping and crying, and parsley means you can make almost any dish look prettier.
I also have some comfort ready meals that I always like to have in the freezer - melting middle smoked haddock fishcakes with loads of frozen petits pois is my go-to "I'm tired and cold and miserable" supper. You can defrost the fishcakes in the microwave and then put them in the oven to cook.
Also, as a storecupboard standby, I recommend the Merchant Gourmet sachets of precooked lentils. The beluga and puy ones are excellent for making fridge-clearing salads, and the tomatoey French ones are gorgeous just heated through with whatever else you've got.