Like others I try to cook enough for 2 or 3 meals in one go!
Stews Soup Casseroles etc!
I live alone but roast a whole chicken and make it last several meals freezing portions until ready to make into Curry or pies etc!
I make soup using the carcass.
I VERY rarely buy ready made dishes
My hot water is only on for 1/2hr morning and evening which is plenty for personal washing and washing up etc. I have a disabled persons shower which was put in for mum when she was here
and is only heating when in use!

The heating I try to be very careful with and have lovely quilts to use in the winter to curl under watching TV
I do take advantage of multi buys when I can

Margaret