I've got an accessible programmer and programmable thermostat. If the
house is empty during the day I switch to 'on twice'. If I'm in, on
once. If it's very cold, on continuously. Much easier than messing
with the programmable thermostat.

It's just that I prefer not to cut the power completely when "off". I don't
want it getting too cold (i.e. below 10C), even when I'm not there. My prog
room stat is on the approximate equivalent of "twice" on weekdays, the
middle of which can be filled in by pressing a single button, if required. I
suppose some stats may have more complicated manual overrides.

Christian.