Subject to approval of the insurance company. You would need to contact them. It comes down to what the definition of unoccupied is. Some allow the property to be unoccupied for 40 days without having to notify insurers and then they will allow full cover until an agreed time if you know when the house will be occupied/sold.
Obviously they don't like to be on a vacant property for a prolonged period of time. Worst case they reduce cover to Fire Only. But it really is one to speak to your insurer about.
If you haven't informed your insurer that the house is vacant and complied with their instructions then it is unlikely that they will pay out in the event of a claim.
They will most likely tell you to turn off the water and drain down the tank and also to turn off the electricity.