I'm waiting on shoulder impingment surgery & rotator cuff repair, I'm now getting pain in the side of the neck would this be causing the pain there?

Yes. It is possible that pain caused by shoulder problems is referred to the neck. Make sure you mention this to your surgeon before surgery.
May be muscle spasm . When your shoulder is injured it is quite common for the trapezius and other muscles to get tight and painful. If this pain were shooting down the arm it would be more concerning for a true neck problem. However, if you have a known shoulder problem and now have neck pain on the same side it is probably muscle pain. In any case it is worth bringing up to your surgeon before you go to surgery.