Welcome to Workshop. We're pleased you could join us and look forward to reading all about your home improvement projects and plans. Feel free to post anytime you need a hand.
I know first hand that it can be very difficult to track down where and when water gets in when you discover a roof leak. Hopefully some clever Workshop members like @royq, @gippslandhome and @LePallet might have some suggestions for you before you engage a plumber.