If you are talking about the main 24 hr weekend that is coming up? The only way you can get out onto the circuit on this coming Friday is to be invited through the ACO via your car/touring club.
2004, the Ferrari owners club were invited and it cost 700 euros for three laps of the track at 07:30 am.
Or if you want real value for money wait for the Classic in July its just 100 euros and as long as there is space and you've got the cash you can do it all day in theory.
My avatar is the result of one such day with the moggie owners! Ferrari Spider - can you do the full circuit on Classic day? Thought it was Bugatti only? Not that it's too crucial as at least u can do the non-public bit.