If you dont get a landing clearance,dont land! (my airline minima for a go around if no clearance was 50 ft RA)
However -if an aircraft has just taken off and blocks the GA path/altitude
-you are unfamiliar with loss comm procedure of the runway in use(reading barby magazines rather than your jepps manual)
-you have a technical problem that would make a GA problematic(flight controls/low fuel/emergency)
-you have no clue what you are doing
i suggest you land and be ready to answer many questions and fill in forms,,ESPECIALLY if ATC had a valid reason not to issue you a landing clearance.