Figuring it would be best to get his first day of classes off to a good start by being available to his students, Aziraphale is in his office. Which looks a lot like a very small library, actually. But there's a comfy-looking couch against the one wall that doesn't have bookcases, and also a couple of comfy-looking chairs near the one occupied by the professor. There's no desk, but there is a table nearby, which holds Aziraphale's tea.

What, you expected an actual office-looking office?