Thanks to all who replied. I appreciate all the comments.
The dealer fixed the fuel leak problem. Apparently a perished 'O' ring, and they adjusted the sunroof. The sunroof is now flush with the metal roof when closed.
I'm new to diesels so this is a steep learning curve. I'll get under the bonnet on Saturday and familiarise myself with this strange beast.
The USA forums and YouTube videos are also very good.