It took us a while to find an insurance company willing to insure our empty house before we moved in especially as we were going to have some work done on the house before we moved in.
But a friend suggested we try Coversure Insurance Services, http://www.coversure.co.uk
and they arranged our insurance through Gresham Services Ltd. It was pretty expensive though but we didn't really have a choice as we couldn't find any other company able to offer insurance if building work was being done to a vacant property.
Hope this helps.