GPX and PDF downloads of the route
A PDF of the route notes is available here
The route is mostly B roads and minor roads. There are some fairly major climbs to do along the way, but plenty of flat sections to recover on. The route avoids big towns. Some of the sections have uneven surfaces and there is one unsurfaced section near the start. These will be mentioned in the route notes and caution is advised, especially on descents.
Two Tunnels: code of conduct
The Two Tunnels will be largely empty by the time the Exmouth comes through. Please read the code of conduct for the use of the route, though. It's straightforward stuff.