There was going to be a kit car tour ending there (and still may be) but that's a bit up in the air at the moment, so I'm formulating my own plans in parallel.
My thoughts are to stay here:
http://en.chateau-de-chanteloup.com/It's about 20 minutes' drive from the circuit but it's pretty, clean, has a decent bar and restaurant, hot showers, toilets that flush, grass to pitch your tent on, and so on. You can camp in the thick of it at the circuit, but you'll find none of the above there. Given that Mrs. KW will be coming, camping at the track is going to end badly if I try it.

The owner is a bit of a petrol head, so is happy for car clubs to camp there and, indeed, for the main Le Mans 24h it's full of like minded nutters, without the stag do's p*ssheads and other rubbish that has invaded the track camp sites. Not sure what the classic is like, as I've never been.
In the past I've done the fast cat from Portsmouth to Caen, Cherbourg or St Malo as it's then a leisurely afternoon's drive to le Mans (100 miles ish) with some slack to allow a more scenic route hacking around the "D" roads. The crossing to Calais is cheaper but then it's 120 miles to Dover, 260 to Le mans and all boring motorway.
There's also the option of a slow overnight boat to St malo with a bar.

Could do a long weekend out and back or a little more of a tour with a couple of additional overnight stops.. Whatever suits.
More about the race event and tickets here:
http://www.lemansclassic.com