Alan,
So in effect you are conceding that there is nothing in control but long chains of cause and effect whose complexity can give the illusion of control.
I'm not "conceding" it, I'm just telling you where the reason and science leads to.
So my original logic was correct in implying that in order to exercise real control over events we need to have something non physical to implement that control.
Flatly no, because you have no idea what you mean by "real" control. For reasons known only to yourself (but I suspect to prop up your religious beliefs) it seems to be important to you to assert some quality you call "real" and by which you actually mean in some unexplained way independent of cause and effect. As no such thing is required however in order for us to function with the everyday appearance of "free" will we can safely carry on acting as we do without that assumption being necessary at all.
So we have two possible scenarios.
We exist in a world in which every event is pre determined by scientifically defined laws and our conscious perception of such things as manipulation, control and choice are all illusions.
Not quite, but close enough for this purpose. Those "laws" may or may not be scientifically defined, but there's no evidence whatever to suggest that we possess (or are possessed by in your world?) little men at the controls who tell our bodies what to do, but who are also in some way independent both of our bodies and of the constraints of cause and effect.
Or we exist in a world in which entities of conscious awareness (such as us) can wilfully interact with this universe by some means which has not yet been discovered and can't be explained by current scientific knowledge. This means of interaction would necessarily have to be non physical in order to escape the laws of cause and effect which apply to physical entities.
It would mean no such thing - that a conjecture cannot as yet be explained "by current scientific knowledge" says nothing to the possibility of the "non physical". You're just trying a variant of the god of the gaps fallacy here. In any case, as such a conjecture has neither reason nor evidence to support it and the current state of scientific knowledge tells us that the universe is determinative despite any appearances to the contrary, fun as the speculation may be you have all your work ahead of you still to demonstrate that it's anything more than that.