I did a few laps over a weekend in my Octavia vRS. A lot of fun, but a couple of things.
You get a smart card now that you load laps onto. You can use them whenever. We bought 4 laps and used them over the course of the weekend from Friday to Sunday.
Even in October the weekends are extremely busy. I felt ok in a car, but on a bike I'd have felt a bit exposed. I'd go on a bike, but during the week.
We stayed at the centreparcs (or equaivent) a few miles away. Close to the lidl for cheap beer and great value for money. The road to and from was just as good as the circuit.
You must go to the pistenklaus for steak on a hot stone. Good food and great memorabilia.
I had someone in the back who knew the circuit well which really helped. You can't really do that on a bike, so from talking to people there they but a racing game with the circuit on and learn it that way. Be aware that you won't get an idea of the hills or the road surface though.
Don't be an hero unless you're loaded. You won't be covered by your insurance while you're on there and it can get VERY expensive if you crash.
When were there the circuit was booked out on the Saturday and we got to see loads of exotic sports cars going round, which was a great break in the track action.
Oh and this is my 2nd lap. It was a LOT of fun...