Good use if energy? Not really. While better than mining and wasting the heat, it would be more energy efficient to use heat pumps and more insulation. Just less profitable.
So insulation wise, the house is a listed cottage so there isn’t much more that can be done to insulate it.
As a thatched cottage you can’t put solar heat pumps on it so the only option is ground source heats pumps which would cost £30000 which is just unaffordable.