Paul Clifton posted a diagram for me on the Deisel section. I had a flash of intelligence in the middle of the night, and had to go out and try it this morning.
Basically, I put molegrips on the threaded hollow bolt and rotated the hollow bolt out with the oil filter attached.
I can't save the hollow bolt, and I even in the vice I still can't seperate it from the oil filter - but the oil cooler should be fine with a new gasket on.
Just got to put it all back together now and refill with oil and coolant
Thanks everyone.