Thanks again for the help. I think I need further clarification on this part because it's making me a little nervous. So I did as you said. I now have 2 different needles on here, but I have a feeling I shouldn't have knit those stitches that I put on the stitch holder. I think I'll take those off and slip them back on to the stitch holder as when I finished my purl stitches (if that makes sense - please clarify if this is wrong).
Furthermore, I'm confused as to which shoulder I'll be working on. Should I be doing the actions described below on both?
R1 (WS): Purl to last 3 sts before neck opening (what I put on the stitch holder) and then last 3 - p2 together and p 1 so that in total I'll ave 28 stitches remaining on this needle. Then I repeat this but in a backwards fashion for the next needle? Such that the side closest to the neck is p1 and then p2 together and then the remainder just purled?