Hi again, and good morning!
The A30 is only a "popular route" for anyone wanting to get a move on and do a sub 10 day LEJOG, though most folk don't use much of it as it's noisy and boring.
My advice for speed is to use the A30 all the way to Exeter, then head north through the city and exit on the B3181. This is the Old A38. Take that road to just east of Tiverton, and it turns into the A38. Follow it to Gloucester.
From Gloucester, head NW on the A417, or if you've had enough of main roads, use the B4215 and A4172 to join the A417 further up. Follow A417 to join the A49 for Leominster.
Follow A49 all the way to Preston, turning off for Chester! - then A6 all the way to Carlisle.
If you don't want the main A30, follow these:http://www.bikeroutetoaster.com/Course. ... rse=137516
LE to Okehamptonhttp://www.bikeroutetoaster.com/Course. ... rse=228070
Okehampton to Wellington
Hope that helps.
Mick F. Cornwall