While we'll have to pay a fat fee to the landlord for getting this done for us, in the long run it will mean, on a monthly basis, that we will have a bit less to worry about with our monthly bills. That with the reduced rent cost in the place we've moved to should mean a bit less sweat on our brows come the monthly bills.
I have celebrated by buying myself a completely garish raincoat, with a hat to match. It's the first new thing I've bought since Christmas and I'm looking forward to wearing it through London spring showers (with a little bit of help from lastwordy_mcgee, thanks!).