Are you allowed to wait at the nearest junction for the possibility of making a U-turn within the lane dividing the roadways?

Why?

At this junction, you may wait in the opening through the central reservation to give way before completing a U-turn. This stop is required by traffic conditions, so the general ban on stopping at junctions and on central reservations does not apply.

art. 49 ust. 4 Prawa o ruchu drogowym