I've been really impressed by the cavity wall insulation and the double-glazed front door. They've made a tremendous difference and the house is staying warm enough overnight that I only put the heating on when I get up. I used to have to set it to come on for a while in an attempt to get the place warm enough to venture out of bed.
It will save us lots of money, I'm sure, which is good because we're heading towards retirement and the consequent huge drop in income when we have to live on a pension.
But we seem to have a thaw here. It was raining earlier and I can hear dripping from outside. I'm just hoping the temperature doesn't plummet overnight and freeze everything solid.