I'm doing Reading. I'm doing a trail 20mile race the week before that. Big hills it will be anything but a race!
Last year I raced Reading a few weeks before London. I don't think it did me any favours. My plan this time is to hold marathon race pace for the full 13miles. I'm doing it with friends so it'll be a win-win.
The book is good as reference and worth a read when you construct your plan and a good reminder every so often what you are trying to achieve with each workout. There's some of his really good lectures on YouTube.