Unless anyone can offer a better route/experience, I'm assuming Paris Charles De Gaulle will be your best airport. As others have said there is then a high speed train (TGV) to Le Mans. Depending on when you would be arriving (and as long as it isn't on the Saturday when traffic is a nightmare!!) I'm sure that in return for a few Turn 10 passes at Sebring we would be able to collect you and take you to Maison Blanche (the main camp site where most CA people stay) and offer you some real CA hospitality!!!