Check in the roof Tony and see if the tank has any water in it. The cold main feeding the tank may have frozen. Check also that the ball valve is free to move up and down by pushing and lifting a couple of times.
Remember to walk only on the wooden joists and not to tread on the plaster board ceiling. If it is frozen then try to find a stop tap that wil isolate it till the thaw (airing cupboard maybe?) and remember to turn off the water if your going out because if it thaws and it is burst you could have a flood.
charity, December 2010
