Thanks. I've done a lot of research on the trail and read half a dozen books, including Walking with Spring, As Far as the Eye Can See, A Walk in the Woods, etc. I'll have a look for the one you mentioned.
I've wanted to do it for about three years now and I reckon I've got another five before I will get a chance, what with getting time off work and funding it. That gives me time to get fit and get the necessary gear sorted out. I was thinking it should take about 6 months, hopefully a bit less.