Has it got a full LR main dealer service history? If it has, Land Rover will honour the head gasket failure. The dealers don't publicise this, so you have to pressure them a little. We asked this before we bought ours and got it confirmed before any money changed hands. Don't pay the bill until you have questioned this, you should not have to pay at all.
It is a known issue with the K series and Land Rover are the only company who have owned up to it. There are MGF owners having to pay bills for a blown engine because MG Rover still won't accept there is a design fault. The problem lies with poor servicing usually, anyway. It is critical that the system is bled correctly. The coolant capacity of this unit is very small, so even a tiny loss will cause hot spots around the engine. The steel head gasket then weeps and accelerates the water loss. If this goes unchecked, the cylinder liners come loose and .... bang! Engine failure.
Go back to the dealer and get them to check with LR about the warranty.