So I checked my epic launcher and I was not running the latest Unreal Engine.
Downloaded the new version 5.0.3 and played for over 90 minutes with no crashes.
I’ll do a longer trial when I can.
Edit. Played another 90 min session approx and no problems.
I would never have thought of updating the Unreal Engine in my Epic Launcher when I play CE through Steam until a mate explained it, but apparently there can be issues between the two platforms.