More often it’s the amount you have to buy rather than the cooking bit.
Fish can be a problem; it rarely comes in packs of one and normally has quite a short use by date.
When I buy my River Cobbler it comes in a pack of two with about two or three days life, so I usually open the pack, separate the two, wrap them individually in Clingfilm and put them in the freezer so that I can use them when I want one by one.
Just a point about freezing fish, I find personally that it is not as good as eating it fresh on the day of purchase, something about the texture just a bit dryer. I normally don’t keep it any longer than a week in the freezer for that reason.
When I buy chicken I like to buy it whole and portion it into breasts’ drumsticks, thighs and wings, then boil up the carcass for a lovely stock, stew or soup. Sometimes when I fancy having a roast chicken I remove one of the breasts as you can see in my post One Breasted Chicken then I freeze the breast or use it in another dish.
Look in your local supermarket and compare the price of a pack of two chicken breasts to a whole chicken, you will find very little difference.
I don’t buy cheap food I just buy real food, by that I mean; it is tempting when you live on your own to buy convenience food like individual ready-made meals, frozen pizzas and so on. In my experience although you can get some cheap deals on convenience foods you generally have to pay more if you want it to taste any good. I buy fresh meat, fresh fish and fresh vegetables then I take them home, chop them up and make them into something that tastes a whole lot better and it’s a whole lot cheaper.
When you live on your own you are responsible for all the household chores; washing, ironing and cleaning the house so taking into account that you have to earn a living as well you haven’t got a great deal of time left for cooking.
Just a bit of fun
I set a couple of hours aside on a Sunday to cook most of the meals for the week, in other words I make my own convenience food.