I have been a few times - you will not have any issues.
In the past I think they have always issued special instructions for the week end so obviously you will need to have a copy of these. There is nothing very exciting in them although they set out the arrival and departure procedure. Not surprisingly there is a significant hike in prices for arrivals during the race.
They usually lay on transport to and from the airport to the gates (at extra cost of course); it is walkable but a little bit of a hike.
In the past from the airport point of view it has always been pretty well organised with plenty of parking on the grass. I usually go justt about due North from Le Man crossing the coast around Deauville - there is really nothing at all in the way to effect other than I seem to recall one small danger area about half way between the coast and Le Man.
Oh and obviously there are plenty of helicopters buzzing around and other traffic so you need the usual eyes in the back of your head.