It's been a while since I've posted here so just a quick update. I'm still following the training runs as calculated by TrainAsOne, which have been a mix of different speed workouts and longer economy runs.
I ran a full half marathon (plus a bit more besides) the other weekend in 2 hours 14 minutes, which was being done at a manageable pace. I was feeling a bit tired towards the end of this run but I'm now thinking that I might be able to try and pace myself to a sub 2 hour time when I run the race in the middle of September
I am missing doing parkruns though, because the plan gets regenerated when I do them (sometimes with drastic changes and cutting long runs back by a lot), I've decided to ignore parkrun because I feel like I really need to keep doing the long runs to train myself mentally for the half.