Dazza95

Nice work guys
Just to close this one out for anyone experiencing problems as per my initial post; the first thing to do is to scan for fault codes. The fault codes and advice on here led me to check the wiring to the compressor (more specifically, the N280 control valve), this wiring was damaged and repairing it got the compressor running.
The second issue was the cooling fan only operating on high speed, for proper and correct operation, it should work at low speed when the AC is running - it shouldn't pulse at high speed. I suspect the issue with mine was the resistor for low speed within the fan as described above. A new fan solved the problem, however if your low speed doesn't work it could be other things such as the fan controller, wiring etc. To check the fan(s), with the engine running, put the AC on and turn the temperature knob all the way to the left, the cooling fans at the front of the engine bay should run at low speed (it may take a minute or so to come on). Low speed operation is pretty much silent, high speed you can hear from the car. If using VCDS, check meas block 01 and 02 - 'cooling fan stage 1' should be on. You shouldn't have any compressor shut off codes in meas block 02 for the test to be accurate.
I monitored the system today using Meas Block 01-04 and with the system set to full cooling, the temperature at the centre vents went as low as 2c after around 20 minutes. The cooling fan stayed at low speed thoughout (stage 1).
Hope this helps, I've learnt quite a bit about the system in trying to get it all working correctly.