Not sure about windows but there are (or were) boiler schemes managed by energy providers.
That said you'd almost never be better off on benefits than working, although it can sometime feel like it. Life on benefits is hard unless you believe the media / stereotypes. I'm all for supporting those in need, I just feel like they're it the only ones that will be struggling. Yes, afford more pay more, and not even adverse to tax rises to fund better services but feel like lot of people will be on squeezed incomes because of mortgages and energy cost and there will be very little support for them, but we're in it together.
Our heating has been in for 3 hours this year and our house is cold, we can afford it but we are choosing to not overspend in case of worse times ahead so warm clothes it is. But when it gets colder we'll put it on as we don't want damp - lot of people won't have that option. At current process it's almost a quid an hour for heating which is wild. I used to berate my girlfriend when the smart meter said we hadn't spent over £3-4 a day combined, I'd kill for that now