sorry for the delay. because my sons clio was old and he never used the sunroof,the only option was to silicone sealer all round the seal to the glass. a bit of a overkill but it sorted out the problem.
doing the same as you, going to the south of france and stopping at nice.went down about 3 years ago in my (300zx). had a great time. me and the wife are just looking to book up asap. mind you she says, where am i going to put MY luggage?
what we found on my sons clio was between the seal and sunroof glass at the front was a small gap allowing water to seep thru, leaking onto the front seats. (does it leak more when driving).
its quite strong gusts at the moment and its just started to rain as well. just spoke to a mate who's a tree surgeon, whos on call out for herts/beds. council/police road clearing. and he is sitting at home waiting for call outs. (busy night ahead)