JTL - you likely wont find any moisture round the sunroof even if it is that. Check the roof lining by the roof pillars - thats where my lads sunroof leak appeared.
The other things to check are the radio aerial seal and the drain holes in the bottom of the doors.
If you google for water leaks in the Clio you will find loads of people with the same issues and usually it is, as it was in our case, the sunroof..
