Sorry for the seperate posts, but its better to keep each issue in its own thread i think.

Another issue i've got is the steering makes a sort of groaning noise when turning to the extremes of travel. It also feels fairly stiff especially at low speeds.

When driving its mostly fine, but navigating a car park for instance where your turning to full lock it makes a weird noise. I guess i should try to record the noise as its hard to explain!

Adjusting nut too tight?

The answer to groaning could be:
"They all do that" depending on how loud the noise is! The system needs to dump a bit of fluid pressure when it reaches the lock stops or it would burst seals and things. A fluid flush would be next on the list, in case the fluid is contaminated or the wrong fluid (should be Dex3).
As for stiffness, as Ferry says, the adjusting nut could be tight.

Tried to get a video, as usual it was proving stubborn :P It only made it once for a short time:

https://www.dropbox.com/s/ziikv1ok8rktht8/2017-04-12%2016.27.45.mp4?dl=0

I dont think its hydraulic. It sounds like its inside the cabin, unless its vibrating up the column shaft or something. Its not the lock-stop/PRV groan that is common with PAS systems. Its movement related.

I sorta thaught it might be the steering damper originally, as it looks to have been leaking and i figured it might be knackered, but it really does sound like its inside the car :/

If you can spin the steering wheel with the flat of your hand like that, I don't think it's overly "draggy".
Can't hear any sound on your vid though. :(

You sure? the noise is unmissable :P

around 3-4 seconds, the last half turn of the wheel before it hits the stop.

The rest of the video is just me silently twirling the wheel as it didnt want to make any noise.

I can definitely hear something. I'm not sure what it is but it is there and you're not going mad :P