So other than for the GP the model sounds like every other track when it comes to hosting events. Clubbies run themselves there too. The other bigger series have the same model at other circuits as they do at Silverstone.
The only difference to other tracks in UK is that they hold some bigger events because they are the only track big enough to do so as you say.
If they dropped the GP, and surely that isn’t a suggestion, they’d operate much like the rest. Except it might not be feasible due to the size?
It’s fashionable to be nasty towards Silverstone. Hell it’s fashionable to just moan about everything in Motorsport! Ultimately it is just that they are the only venue that can host the GP. Shear scale means that dominates, but if we ignore that they have pretty much the same approach as anywhere except they have a bigger infrastructure.
FWIW I’ve had people turn up to testing while I’ve been there (but not come with me). Still that was a few years ago. I guess that it has changed. Which must disappoint the half a dozen people that want to do it! I guess that it isn’t worth the hassle. It’s a big place to police. I wonder if it was spoilt by the few.