I was on a predominantly off-road bike ride from Chippenham to Manchester (not all in one go of course!)
Anyone whose interests include cycling and railways could check out the Great Western Randonnees series of rides. They won't be to everyone's taste, they're from 60 miles up and be warned that some include ferocious hills (but some are quite flat), but most have some sort of railway connection and could be used as inspiration for your own ride ideas. One was organised not so long ago to coincide with the last
HST▸ from Paddington and included a helper on the station concourse dressed up as Brunel! (it was about 3 o'clock in the morning so this didn't interfere with passengers).
http://www.pedalution.co.uk/blog/gwraudax/The organiser is a friend of mine.