How much does double glazing on a four bed house roughly cost?

You should get change out of 6 grand.
about £3500
about 4K
You should be able to get this done for 10000 pounds, be careful though. When double glazing my 3 bed house the quote came to 13500 pounds, but when I haggled I got them down to 5k, so dont accept the first quote!
It depends who you go parents were quoted everything from £3800 to £16000 - that was for 11 windows & 1 door.
I just did my three bedroom house. They wanted $15,000 but I was able to get them down to $12,000.
If you are up to it buy the windows and fit them yourself a lot cheaper than using a company.