I'm blogging from Waterlily. It is -2c outside and a warm 22c inside.
When we arrived there was no water coming from the taps, but the pump did cycle and pressure the system. We lit the fire, topped up the antifreeze in the header tank of the central heating (back boiler from the Squirrel) and boiled up some water we brought with us. We left the taps open with the pump off and after about an hour they started dripping followed by running water. We gingerly turned on the pump and it pressurised the system again and stopped -hopefully indicating a pressure test on an unfrozen system.
I think we just about called it right. We will keep the fire in as best we can while we have this cold weather.