Hi, done it 23 times but the last time was over 30 years ago so think the route has changed slightly since then. One year did it every weekend for 8 weeks leading parties of scouts. We used to set off around 1.00am to get the first part over in darkness, but due to familiarity,navigation was not a problem. Times have ranged from 14 hrs to 23 hrs ,(that was in full on winter conditions ), and one there and back walk that took 30 hrs. The main thing is to make sure you are physically and mentally ready, and if possible have a support crew meeting you at road crossings to supply food and drinks, also means you do not have to carry supplies for the whole walk, Best of luck and hope you enjoy it as much as i did