I feel for you Alison.We were woke up to our cat Screaming at the top of its voice(if cats have a voice)to find water pouring through the hall ceiling.Luckily the water had found its way through the smoke detector mount holes so we had no cave in. Im more than capable to sort the problem out so It was no problem to fix.I hate to think how much a plumber would have Charged.My advice to anyone is buy the B+Q diy book.
http://www.amazon.co.uk/dp/0500515514/? ... 0500515514
Not that I recommended anything else from their over priced junk stores(read crap cheap bathrooms that are a swine to fit).
Anyway turns out my problem had been half caused by the idiots whom I trusted to fit my new facias and guttering(I should have done myself but I would struggle on my own to lift the stuff).They had pulled the overflow pipe out of its joint so when the ball cock stuck open in the header tank the water flowed down our hall way rather than down the pipe and out side