I came across sources of information that lead to me to conclude that Perforce Helix Cloud was not suitable for integrating directly into UE4 editor:
- Perforce Helix Cloud requires streams.
- The Perforce integration with UE4 does not have stream support.
It would probably be possible to use Perforce Helix Cloud with a UE4 project by using a P4V is an intermediary, but I want true integration with UE4 and so have instead looked to Assembla for hosting.