Then the electrics, then the heating
Water and electricity in the same ceiling void is the part that stops being a plumbing problem. If water is anywhere near a light fitting, a socket or a consumer unit, turn the power off at the consumer unit before you deal with anything else. If the leak is on the heating rather than the mains, turn the boiler off too, because a system losing water will keep pumping it out until it locks out on pressure.








