Move what can be damaged
Furniture, bedding, electronics and anything valuable should come out from under the wet area. Put down containers and towels where they will not create a trip hazard.
Ceilings can hold water
A bulging plasterboard ceiling may be carrying more water than it appears. Keep people away from it. Do not stand underneath and prod it to see what happens.
Tell the roofer what changed
Mention storm damage, missing slates visible from the ground, how quickly the water arrived and whether it is still raining. That helps them judge urgency and what equipment may be needed.
After the immediate leak
Once the ingress is stopped, allow wet materials to dry and keep an eye on staining. A repaired roof does not make saturated plaster or insulation dry overnight.