Amazingly Aprile I sorted it myself. I have a condensor boiler and after searching on the internet I found that it could be the outside pipe was frozen. At 8am this morning I was out in the garden with a kettle of hot water and a hair-dryer. Did the trick and by the time the plumber arrived it was back to normal. He said lots of people are experiencing this and altered the pipe so hopefully it wont happen again.

Hope you'll soon be warm again.