Well you can accidentally find Camelot, it's actually on the grounds of the Welsh Estate held by Bedivere. Below it actually. The entrance is through a deep artesian well. The groundwater of the well runs deep into the underground cistern the ruins of Camelot sits in, buried beneath centuries of history. So if you swim through the cold waters in the dark depths against the flow, you'll reach Camelot's Courtyard.
That being said, Bedivere would not allow humans to pass freely without being either descendants of the original knights and can prove so with a pedigree stretching back to one of Arthur's men. Or you could also attempt to become sworn in as a Knight, either by taking the challenge or getting Merlin's approval.
Regardless this is assume Bedivere doesn't slay you within moments of find you. Most other vampires leave the place alone due to the Judeo-Christian imagery found all over, as well as the staunch protector of its halls. Merlin also made it nearly impossible to scry into, so blueprints and diagrams of Camelot do not exist, nor would any scans of the area save for a physical presence be able to witness it.
And since the only above ground entrance is the well, and there is no valid reason to dig in the historical Welsh estate held by Bedivere via proxy, it also limits how Hive could storm into Camelot <_<.
If Adam wants the key, he'd have to send a human into Camelot to fetch it, and make sure the human is invited by Bedivere, or Mithias who could give the human an escort through the halls.
One more thing overall, I'd like to throw into the pot here worth mentioning, can we try and limit the "Conveniently pulling information out of our hats" routine? I mean I guess technically a quick informative dossier would be acceptable within the means of "intelligence gathering" but limit the information to stuff that is selectively known about the target such as information which would be publically available. Like while Bedivere knew about Adam being associated with Yamato, he didn't know Adam's shoe size or collar size. Nor where all his encrypted secure communications and information centers and their layouts to successfully infiltrate them. Given that Bedivere controlled MI6, or the British Intelligence Agency, he'd have such information at his fingertips in the game of espionage. But I played it out that even he doesn't keep tabs on everyone and everything but has pawns lower down that probably would. Yet he only skims through the summary compiled which is pretty much all that the Author of the party allows me to know.
Anyways, back to work. I did not have a terrible fish sandwich today. :)
