Just so I can remember where to find it, here's a link to an on-line map of the C 2 C, including OS maps down to 1:50 000 by a chap called Mickey. (no relation)
He posted on the excellent SherpaVan hosted C 2 C forum.
And talking of on-line maps, I found out the OS is phasing out its well-useful Getamap service (maps down to 1:25 000) and replacing it with an OpenStreetmap style of map (with NO contour lines or other relief information. If you want proper maps you have to subscribe. With money.).
I can see why they've done this, to make more money. Getamap, although you have to be able to run Silverlight (so that basically means a Windows computer), was quite handy to just quickly check out a route when no map was to hand. You could even draw and save your own routes.
If you wanted to use it properly, you could subscribe and get full features and full page printing.
This new OSMaps is not nearly as useful. Also with Bing using OS mapping and OpenStreetmap showing contour lines on their Cycle Maps layer, I can't see there being many takers.
Walk Highlands uses excellent maps.
By the way, Mike Knipe uses http://www.plotaroute.com/