Discolouration on the ceiling
Generally this shows up as round patch on your ceiling, due to water dripping onto the ceiling and soaking through, making a water stain.
Light shades and light bulbs fill with water when it rains
More common than realised, when water leaks into the ceiling it will often run down electrical power cabling and end up in the light fixtures in the ceiling.
To have your roof professionally inspected please phone Brays Roofing