What to do over winter (pipes)?

The property I am currently in is very old & has a Glow-worm 21-30 which has no thermostat or anything-it is just switched on at the wall. There will be no one in the property for 5 days over xmas and am wondering if there is anything that can be done to stop the pipes freezing up and bursting over this time as the heating cannot be set to come on. I was thinking of leaving the heating running on its lowest setting over the period but have been told this may not be a good idea.
Thanks

Rachel James
December 2004