welcome to the forum and the damp world of Clio sunroofs, theres a few sunroof "How to's" in the Clio FAQ, that are well worth checking. Good guides with pics. Just click the big blue box below this message
Used some good brand all purpose clear sealant between the sunroof trim and the bodywork and hey presto, no leak. Had a good test today, persisting it down and 100 miles on the M6 resulting with dry trousers, hurrah.