I've decided split toning is much harder than it looks! I tried to do this one manually but failed - I couldn't get it to look how I imagined. In the end I did a b&w conversion through PS using masking to keep the two red tomatoes red (the other ones are still green). I took the pic back through to LR and used one of the presets from there to get the tones I wanted and adjusted them through the tone curve. It was fiddly and I'm sure there are easier ways to do it, but it was good learning, especially seeing the colour settings on the tone curve from the original preset. P.S. The tomatoes were hanging on the plant when I took the photo so I had to change the background to plain black to match in with the other shots I had planned for this week.
After much debate with myself about whether to carry on with my Diploma I finally signed up for the next paper which started on Monday. So now I'm back to spending all my free time studying and the first assignment is due in a few days' time.