After taking a month off (to write an entry for this competition), I have returned to first draft of my book, and it's not as awful as I thought. In fact, I'm quite pleased with the last few chapters and the ending - perhaps only because they seem to need minimal rewriting.
Elsewhere, however, much more is needed. Chapter 19 didn't exist apart from a few notes, so I'm currently writing that. Then I will start rewriting from the beginning, working from the printed copy of my first draft, which I have been annotating.
I've also decided to swap the order of two chapters, and completely delete chapter one. I'm now not sure how the book will start, and how much extra I will have to write. The word count is pretty low - currently under 65,000 words, which is short for a novel. I had originally intended to reach 80,000 but the idea of having to write an additional 25% of the existing book seems way too time-consuming.
As things stand, I hope to have the second draft finished by March 2018. At that point, the intention is to start sending it to agents and publishers. (I say that like I know what it actually involves. I suppose it starts, as all things do, with Google.)
There are a few people I have a vague connections to that could potentially give me some leads, but I'm quite looking forward to sending it out unsolicited to get some reaction and feedback. I reserve the right to change my opinion on this based on the nature of the reaction and feedback.
But before that, there is plenty to do to get it into shape.