Success!
So i put 12v direct to the fans again today.. I connected up to the bullet connectors on the fan loom as opposed to the plug at the back of the radiator and the fans fired up.
I checked the relay in the fuse box, found which one it was by shorting across the fan switch, its in good condition, no signs of drawing to much current thankfully. The bullet connectors were a but crusty so i cleaned them up, Let the car run up to temp and the fans came on as the needle got past the O on NORM. I wonder if there was a voltage drop across the crusty bullet connectors.
Job done.
Still will fit a new fan loom as well though.

Thanks.