FOUND THE MOTHER! Problem is solved, managed to trace the fault to a bad earth on one of the fuel injectors!
For anyone who might have the same fault in future here is how i found and corrected the problem:
Persistence in reading the ETM showed the relay was supplying the 8 FEUL INJECTORS and the air flow meter. The workshop manual also states this in plain english, as i'd written down here before, but the circuit drawings had me confused and not able to see what was right in front of me!
So to testing, Firstly i pulled all 8 connectors for each injector (located above each cylinder) and tried starting, the fuse blew, so it was not a fault with the injectors themselves.
Then referencing the ETM and Workshop manual to trace each injector connector to the appropriate pin on the other end (ECM), Using a multimeter to test the resistance between the output pin (from ECM) to each of the two pins at the injector end. This was repeated for each of the 8 injectors. I found that all the readings were near identical except one injector would read 150 ohms on the ground pin (compared to the other ones not registering a value)
I could see that cable went to one of either two earthing points, I had previously moved all the cables from one of those points to another one after snapping the thread, and knew it was a now good connection, so it had to be the one (under fuse box behind ECM housing nearest to RH wing) I cut and extended the cable to another earth point and tested the resistance, it read like all the others.
Plugged all the connectors back in, put a new fuse in and gave it a go. Bingo!!!!!!!!!!!!!!!!
I have no previous auto mechanical knowledge (at all) so please only take this as reference to my experience. I only hope this helps somebody someday.