We camped overnight at the circuit, which we were allowed to enter after the Saturday qualifying. As we didn't get there til nearly 6:30 there wasn't a lot of room left (we had a large campervan) but we eventually found a spot near the toilets and showers. It turned out to be a great spot as was fairly quiet once the generators were turned off for the night. Most people were respectful and wearing the tags so you could access the campground from the track made it easier than having to pull tickets out every time.
The only thing I would recommend is to have a quiet end and a noisy end as you could hear a lot of music and yelling from the younger groups til quite late. My kids were tired so slept right through it thankfully :-)
Food and drinks were reasonable prices and although I know this comes down to the vendors.
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