Actually, I'm a bloody top 10% slightly right of centre and I found marriedinwhite posts a bit damned much.
Do I know people who are feckless? Yes. I have family who are bloody feckless - I don't come from money. But yes, the steps we took as a young MC couple with not a lot of money to spare but plenty of prospects are entirely different to the recommendations for a family in poverty and renting.
20 degrees plus mornings and evenings in the house is not a insane luxury. It's what I grew up with even when parents were poor, and even in 15% interest periods. I am really sad that some people think (for non-environmental reasons) that this is basking in luxury. On to some suggestions:
I had a uni flat with 11ft ceilings. PITA to heat as a student. Thick curtains were a must, but a lot of radiators are under windows. Unsurprisingly (to me anyway, but not some of my friends) if you put in floor length curtains over the radiator to keep the heat in...you are erm, not.
Ugly sausage dog style draught excluders can make a big difference. My mother bought me one quite recently and I made a face, thought 'not skint' but I tried it anyway. Made a huge difference.
If you are in an upstairs downstairs, close the doors. Heat will gravitate upwards and bedrooms don't need to be as warm as living areas (accept if DC play in rooms may be different, but most radiators also have an thermostat so theirs could be turned up). Be careful where the thermostat sits, esp if you have a combo boiler - we have an old house and it's difficult to find the optimal place to control the house heating, put it in a cold area and our heating is on way more than we need.
Slatternly as this may sound, don't open the curtains on north facing windows. We have shutters and I used to open them in the morning, but now that the morning's are dark I only open my south facing curtains and leave the shutters closed. I air for half an hour at the weekend if need be (we both work out, no kids) but otherwise this makes no difference other than keeping our house warmer, whereas previously we'd have the fire on for half an hour upon getting in most winter evenings.