Look at the pattern
Condensation often affects a broad area. A roof leak is more likely to follow one local route.
Check extract ducts
A bathroom duct ending in the loft can introduce a surprising amount of moisture.
Keep a simple record: one wide photograph, one close view and the date of the weather event are usually more useful than a long description written from memory.
Recheck in dry weather
Moisture appearing without rain strengthens the condensation explanation. A single timber becoming wet straight after rainfall points back to the roof covering.