@WinterMusings Thank you for your reply.
How old is DS? Any SEN?
9, suspected ASD (almost certain ND in some way), waiting for assessment. Forcing it would mean a meltdown, so not an option.
Have you seen the clear stick on film for windows? It's not that expensive & really helps with insulation.
Have looked into it, it's the frames that really suck the heat out and not sure, given the condition of them, how well anything would stick to them.
Look out for special deals on boilers, I think with the move to heat pumps, you'll get some decent deals and it will save you money, so it might not take too long to recoup the money spent.
We've been looking, but the placing of it is an issue, it really needs to be moved upstairs but that really bumps up the cost and involves pulling up floorboards. Looking at the possibility of just swapping out the old one - but we also need a new roof and we can't do both.