I fixed my sunroof rattle myself. It was a loud metal on metal clunking noise just behind my head on rough /bumpy roads and it was getting worse over time. If yours is the same then check as follows:
Get in the back seat and with the sunroof glass fully closed then bang hard with your hand all the way around the roof lining (not the glass) near the sunroof to identify the general location. Mine was on the right hand side near the back. Remove the hand grab handle above the door (do both sides if you like). With the handle removed then you can pull the roof lining down a bit as its only held up with Velcro, then, holding down the roof lining a few inches with one hand you can get the fingers of your other hand inside the gap. Down the sides of the sunroof feel back and forth for the heads of the 8mm bolts down each side holding the sunroof in place, from memory there should be 5 or 6 each side. On mine I could feel with my fingers that one of the bolt heads was actually loose, so I got an 8mm ring spanner and managed to get it inside the gap (by feel only as you cant see) and tighten the loose bolt at least 1 full turn. Even if you cant feel it loose then see if you can get the spanner on it to properly check its tight. I checked all the other bolts I could find along the side of the sunroof and tightened them up too. I put it all back together again and went for a drive and it was definitely fixed, no further problems in the last 12 months.
Hope this helps.