Hy Groucho.
Actually, you got confused. Of course there is a minimum to make a visual approach (ceiling 1500ft and visibility 5000m). Exemple: the MDA is 600ft and the ceiling at this moment is 900ft. In this case, I could not make a visual approach, but I would be able to circle to land.
Again, I said the ceiling is under the minimun required to make a visual circuit, only to avoid answers like: after go around, make a visual approach (crosswind leg, downwind leg, etc). Did you get it??????
Now, if you got so confused because of this, forget about it and focus on what really matters in this thread: I wold like to read more about my doubt: which IFR procedure should I follow and how to execute it?
I'm not talking about only airliners planes... Imagine this situation in GA, for exemple.
So, I ask everyone: Is there any publication beyond the ICAO Doc 8168 and the Circling Approach Discussion Paper??