The Diageo archives are now online for a 3D tour. I have some specific things I am looking for so tonight I decided to look around.
While they don't give the ultra-super closeup or access to individual documents I was hoping for (but was not optimistic to find) it was a fun tour around the physical rooms of the archive. It's split into sections for advertising, bottles, objects, etc.
To view the archives, follow this link and push play on what looks like a movie but is actually the whole thing!