which Sustrans route are you taking from London to Canterbury?
FWIW I would be very surprised if your route is crushed gravel - but clearing London on that ride in that direction will take a long time and is not a terrbly nice ride (I did the London to Canterbury Sportive last year)
I would take a train from London to Tonbridge or Royal Tunbridge Wells and then pick your own route on the small B and C roads - any reasonably decent auto map should be sufficient - it will save some time and put you in to nice countryside with little hassle - riding out of London is never fun
for more details and help (on England and Belgium legs) I would post on Bikeradar: http://www.bikeradar.com/forums/viewforum.php?f=40003
FWIW I would be very surprised if your route is crushed gravel - but clearing London on that ride in that direction will take a long time and is not a terrbly nice ride (I did the London to Canterbury Sportive last year)
I would take a train from London to Tonbridge or Royal Tunbridge Wells and then pick your own route on the small B and C roads - any reasonably decent auto map should be sufficient - it will save some time and put you in to nice countryside with little hassle - riding out of London is never fun
for more details and help (on England and Belgium legs) I would post on Bikeradar: http://www.bikeradar.com/forums/viewforum.php?f=40003