Transit of Reims Champagne Class D has never been a problem for me, although on one IFR transit I was asked to hold for a few minutes at the VOR There are new VFR transit routes to follow, I believe, so you need a current map or approach plate. If I remember correctly, the approach frequency has an automatic recording which plays when you transmit on frequency and advises you when the airspace is cold. Prunay is a very friendly GA airfield and is open at weekends, with a restaurant on-field. Why not get a Jepp/Bottlang trip kit to ensure you have up-to-date info, including customs and notice required? (I would tell you what mine says, but it's a few months out of date)
On an entirely different subject, do watch out for TPAs. Infringements are being followed up.
AA