Ok so it's all sorted now. To all the people that said check your fluid first etc etc, I apologise. That was the problem but let me explain.
I took your advice and checked my fluid, even drained and topped it up. However, because there is no min/max lines I just guessed where it should be. I thought it worked like the coolant tank as in when it gets hot the fluid rises.
This isn't the case with the power steering but I didn't know that until now! When you turn the engine on, the fluid gets drawn into the pipes, thus making the fluid level inside the tank drop (just below the inlet and outlet pipes).
This is where the air was getting in but obviously I just checked the level when not running and saw that it was about 1" from the top and thought if I put any more in, it would overflow!
When I checked it when running it, the fluid was sloshing about and I thought that was normal.
After speaking to the father in-law and him educating me about the fluid being drawn into the pipes, I put in about half a shots worth of ATF in a tested it.
Well what do you know, noise free and it feels fine now. Thanks for all your help everyone at last it's finally sorted.
I hope this can help anyone else that is as clueless as I was. And I mean I put in a really small amount of fluid.
That's what she 'Zed' :-/