Cause of my roof leaking? (Victorian house with photos)
If you want to identify where the leak is coming from, get a buddy and have him spray your roof with water using a hose while your in the loft looking for water.  Have him start from the low point of the roof and slowly work his way up.  Sine you don't sound like a roofer I'd say this is your easiest way to find the leak.
Don't forget to give me a thumbs up so I get credit for helping you.
Good luck