I done courses in Uni by english professors with mainly english speaking foreign exchange students (and they had nothing to do with english literature), and done it without hitches. Granted bit untrained vocally out of habit (not much occasion to speak english), had to at first think extra seconds before speaking. I thought it would be harder/more difficult then it was (speaking bit, not understanding).
But would say its near enough fluently. Without ever passing as english as ones native toungue obviously (due to accent). But yeah, english is fairly easy language, or better yet, a language that we have been droned into heavily by the dominant ango-saxon pop culture.
Little trivia, was talking books with friends, and 4 of us, and 2 of us talking about same books, authors etc. While the third asked about a Swedish book, we were like what? Rest of the time talking about how semi odd it is that almost for a decade, 3 of the 4 of us has read books in english exclusively (not only english original books, but prefering english translation over swedish one in orginally non english books etc), to the point a swedish book seemed odd or foreign just by mentionning it. Its a deliberate choice ofcourse. But yeah, english is VERY much common in several ways, atleast here (I mean, Swedish artist sing in english way more then actual swedish).