...that the oil flow to the filter is via the pipe that goes from the block next to the oil pressure relief valve to the filter head and then through the filter and back into the engine via the opening in the back of the filter head? It might seem like a daft question but I want to double check so that I plumb my remote filter head the correct way. If there's a wrong way to do it...

Yes.

It's picked up from the gearbox through the pick-up pipe then it goes up the round channel in the rear of the gearbox and block to the oil pump.

From the pump it goes to the front of the block past the pressure relief valve to the external oil pipe.

This takes it to the filter and the clean filtered oil goes through the oilways behind the filter head to the crank bearings, cam bearings and rockers.

The reason the oil pump internals often end up badly scored is that they deal with unfiltered oil which sometimes has bits of gear box in it.

Thank you, kind sir - that's exactly what I needed to know