1. Take care in the loft. People really do fall through the ceiling into their bathrooms. If the floor is not boarded, keep your weight on the joists. Take a sturdy board up there and stand on it.
2. All pipes in the loft must be insulated except those which are already under loft insulation or within a tank. Check insulation on your pipes to make sure it is secure. If you find any gaps, use lengths of pipe lagging to wrap around the pipe and bodies of taps and joints. Fix the lagging in place with tape or string.
3. If your tank doesn't have a lid , fit one. Use a proper plastic lid.
4. Check that all the water tanks in the loft are insulated. If a tank is at ceiling level don't insulate beneath it as warmth from the rooms below will help keep the water from freezing. If the tank is not insulated, a purpose-made insulation jacket is easy to fit. Check the lid is securely in place before you tape or tie the jacket around the tank.
5. Check your tanks are refilling properly. An automatic float valve allows water to be replaced to a set level.
As the fill level is reached, the float is lifted by the water and slowly shuts off the supply.