Got sorted, the problem was the alternator pulley.
Jack the front of the car up to give good access.
Put a spanner on the belt tensioner pulley and push towards the back of the car (clockwise).
This will take the tension of the belt for you to remove it from the Alternator pulley.
Then find the part behind the pulley on the alternator shaft which has square sides for a spanner (21mm approx) to slip onto, so you can hold the alt shaft in place.
Now remove the black round cover on the face of the alt pulley and put the splined alt pulley tool into the center of it.
Then just loosen the alt pulley anti clockwise with a spanner or socket on the splined tool, while holding the other spanner in place to stop the alt shaft spinning.
Same method in reverse to fit new one.
Job Done, hopefully now nice and quiet again. :D