thanks very  much - will try them today. Cheers !

Hi Blue-Kat, Welcome --  I think your going to have to get cover for that through a broker, I listed a couple below who do derelict property cover for you to get quotes from.

http://www.brokersdirect.net/vacant-property-insurance.htm

http://www.easylet.org.uk/vacant-property-insurance.htm

They will tell you more about the conditions that must be met, but I bet no insurer will offer rebuilding costs on it.

 My first post here and hope it's OK to jump in with a question straight away.

We have a derelict coach house at the back of our garden. it adjoins onto 4 or 5 other properties.

Currently it isn't covered by our house insurance because of the
state of it. some of the roof came off in the storm in January, but we
couldn't claim.

We are carrying out very basic emergency repairs
but need to have liability insurance in case it causes any damage to
other properties.

I presume you can't insure for rebuilding costs on a house that's pretty much ready for demolishing already? 

thanks