Catch the water
Use a bucket or tray and protect flooring. If water is spreading across a ceiling, move furniture and electrical items clear. A small leak can travel before it drips, so check nearby light fittings.
Electrical risk comes first
If water is near a light fitting, socket or wiring, do not touch wet electrical equipment. Isolate the relevant circuit if you can do so safely and seek qualified help where needed.
Loft access
If the loft is easy and safe to enter, a container beneath a drip can reduce ceiling damage. Stay on proper boarding or joists; plasterboard will not take your weight.
Avoid improvised roof work
Sheets, bricks and ladders on a wet roof are a poor combination. Temporary external covering is a job for someone with safe access and a way of fixing it so the next gust does not turn it into a hazard.