can a combi boiler run hot water when the CH system is empty?

I have a glow worm 30ci combi boiler. A radiator pipe has sheared off (oops) right next to the wall it comes through and I'm not able to mend until later in the week. The CH system is now empty, and the children (and I) need a bath! Is it ok to run the hot water while the CH is empty (the pipe can't even be capped off - tried that one)

Many thanks!