Well, I thought that it would take a week... I'm already done on the first draft in Word. Just goes to show how much you speed up when you're more familiar with the software. Or that I got VERY sloppy towards the end and when I go through it again tomorrow I'll have to make loads of changes. Be that as it may, I edited 35 pages today, about half the document, plus the table of contents, which is pretty good going.
Stage two will be to get some additional material I need from a couple of other people, then check it through again on the PC, then transfer it to the iBook and see if any horrible problems appear. After that I'll have a go at converting it to PDF. Might even be finished by the end of the week, though I doubt it.
Many thanks to everyone who helped me sort out the formatting problems - it really did make all the difference.