We had a similar arrangement, most of our families houses had an outside toilet and a tin bath on the back of the cellar steps door. The bath was filled from kettles on the gas or fire range, the bath was set up in front of fire with a cloths horse behind it with a blanket on for some modesty, and everyone took their turn.
Back at home we used to have a small paraffin heater in the bathroom to stop the pipes freezing, as a child I used to get dressed in bed to fend off the cold, there was always ice on the inside of all of the windows, even the bathroom with it's slight heat.
Regards
Alan