Gsm, I have gas as well as electricity. I am very comfortable and warm
I do think it is a good idea to compare the tariffs and if needed, to compare units used.
It seems that I use a consistent number of units of electricity. I consciously do things to keep energy use low but comfortable eg my freezer is choc a block and when I moved here I bought the tallest most efficient freezer I could, with drawers so that cold air does not fall out when the door is opened. If it empties in the future, then I will fill lock n lock boxes with water and keep them in the freezer as a full freezer is much more energy efficient than empty space
One person, one light, that is all I need unless I am knitting when I also use a reading lamp. Lights are switched off when I leave a room, unless I am going to return soon
Last house was eco -built wrt energy saving trust and a well know university, we had meetings in our house. That house had PV, solar thermal, water harvesting, pellet stove, heat sink walls and floor, triple glazing, ventilation system. Being in an eco house makes a person be ultra aware of energy usage. It was so efficient that we earned more from the house than we spent. All of us on that estate were very proficient and knowledgeable in energy saving