I sacked yesterday off in the end.  It snowed in the night, the roads looked dodgy, and the pipes were frozen anyway.
Today I managed to work after a delayed start.  I disconnected the pump connector the day before and broke it pushing it back in this morning.  I guess it was a bit brittle with cold.  I have a couple of spares, but it was a bit of faffing around.  Finally got going about 11 and knocked off about 3 when the sleety rain became a hassle.
Not the greatest day but satisfied.