I have copies of books by a British nutritionist called Louise Davies, aimed at just such people, suddenly finding their way in the kitchen, and rising from evening classes with recently single non-cooks. The first book was "Easy cooking for one or two", the second, probably, "More Easy ......".

Much of the book did not depend on measuring. E.g. mix the contents of a tin of sardines with an egg and grill on toast.

I tend to make large quantities of casserole and save in "Pour and Store" zip bags in the freezer in single helpings. If I have a visitor, I can thaw two. I also make multiple shepherd's pies etc. It gets over the same thing day after day situation.

Measures are important for baking, not so much for the ordinary day to day meals.

Penny