Most airfields in the UK that have regular helicopter traffic have different circuit patterns for helicopters and planks. Heli's often operate from FATO's or designated heli-training areas that are suitable separated form the main runways to allow simultaneous approaches, circuits and departures. I'n many cases fixed wing would be doing some form of overhead join, and helicopters usually low-level, more direct joins.
The arrival or departure of heavier aircraft will sometimes disrupt us to some extent due to wake-turbulence, but often smaller aircraft can operate to different areas of the field and simultaneously. It changes between airfields obviously but I very rarely find myself on final behind or in front of a fixed wing using the same approach area. In fact I can't clearly remember the last time.