Thanks @Hotfoot - that's a helpful question. Thinking back on it, when I was adding in braking, as I was approaching the corner, I was probably focussing more on the turn point than I was before. Probably what would be more helpful is to remember my 3 step, and be focussing more on the apex once I'm sure I'm going to hit the turn point. Hitting the apex at the desired speed/position is more along the lines of what I want to achieve. Thinking further back, there have been times on previous track days where I've done that naturally, and it's worked well.
I guess in the final drill of a long day, there's a lot to remain conscious of ... 3 step with sideview transitions, fast turns, and then trail braking with tapering off. It's a lot to be actively conscious of.
Anyway, I've got a trackday at Donington Park circuit on Wednesday. My plan is to use the morning session to practice 3 step and widescreen transitions, with only light braking, and spend the afternoon adding trail braking and see how I get on.