The National Art Library, housed among the many wonders of the V&A, serves in all ways to serve the museum's broad subject scope of art and aesthetics. Books, journals, and other materials such as sales catalogues and trade literature make up the art and design collections, with occasional other gems (e.g. Shakespeare First Folio, Dickens manuscripts, DaVinci notebooks) acquired through the bequests of two "gentlemen's libraries," as one librarian put it. I don't suppose you would argue that a First Folio isn't really in your collection areas when it's offered to you.
The public are welcome to, and do, use the library when they wish. There are two main reading rooms within the National Art Library within which readers can go about their work. The many volumes lining these reading room shelves are the reference works of the collection; library visitors can pull them off the shelves themselves as needed without having to formally request them. Formal requests, on the other hand, are retrieved by staff once every hour. Staff will go through the three floors and several rooms of book stacks to retrieve whatever it is the readers need; I really had to wonder at the variety of places all the books are located! Another librarian commented that, while the National Art Library is lucky insofar as it has all of its resources on-site for easy retrieval, they are running out of shelf space. Thus books, books everywhere.
Most of the 60 library staff members actually work behind the scenes, doing things like managing the £500,000 acquisitions budget or cataloguing the new materials the library is always receiving. Only a small portion of the librarians actually work out in the public reading rooms, where they interact directly with library readers.
Perhaps the fact that I found most interesting about the National Art Library during our tour is that library staff do not just field all library reader enquiries--they actually field all enquiries from the entire museum, be they from the public or the staff. As a librarian, I would imagine that this both increases your workload and diversifies it. After all, if you're trying to assist both amateurs and experts, the variety of queries you'll field would seem to be very great. I like the idea of variety in library work and reference questions. I also love the V&A, so perhaps there is more to attract me to this sort of library than I had originally thought.