If the area is not actively published via NOTAM, then you can fly through the area without obtaining permission to do so.
But it is always recommended to be in contact with ATC/FIS.

NOTAMs are issued every day before the expected activity, usually during the afternoon. That is that the evening before, you should be able to count on the issued NOTAMs.
But of course you must check the NOTAM on the day before you go out to fly.

Martin