Thanks everyone for this great response - I haven't planned a route as yet, I was just beginning to think it through as I would like to do the ride as a fundraiser for Macmillan or British Heart Foundation. The only complication is that as a hapless salary slave and with mouths to feed I only have so much holiday time/money I can indulge myself with before it impacts on family so I'm interested to see how long I should look to allow.

As well as the weekend rides I commute a 15 mile round trip 2-3 times a week and could perhaps up this to 3-5 times a week. What proportion of the route is offroad as I guess these will be the most arduous parts , how did you accomplished types split the ride up was it by miles per day or hours per day?