[gfm]

Adam - this will be one of the greatest experiences you will enjoy in your car. So do take care about planning and ensuring the circuit availability as there are a bunch of closed to manufacturer circuit test days.
There's are phone numbers for the circuit and most of the folk on the other end speak reasonable enough English.
There's a well organised cafe/gateway onto the circuit now about a mile away from the museum. But it's all quite a sizeable business and developed area. Hotels, garages, and services are all around.
I would always recommend going on something like an RMA visit because there's a wealth of experience and though not cheap, your unlikely to have serious interruptions.
During the summer, there are traffic jams getting on the circuit and alsorts of untidy mad folk doing stupid things. Motorcylcist spreading themselves like jam all over the place etc. So they do have to close the circuit quite often. Yes, you do indeed visit a ticket office or machine and get your ticket. Even when the circuit is shut for manufacturers, they try and open it in the evening, but it is a long way to go without checking this.
And there's no way you won't go back for another shot. It's quite fun to watch people's/driver's reaction to the place. Most seem to arrive buzzing and excited; most come off at the end of their initial lap MUCH MORE SOBERLY with the wise cracking well in check; it really is THAT daunting. And in the rain, it is EVIL. The cambers and undulations send you all over the place and there seems like NO GRIP.