I'm really glad with all your comments and tips, thanks guys. I'm taking them on account to see when it's possible to match them with what I'm doing.
My impression so far is that trying to follow always National routes from Sustrans it makes the trip very slow. I think that these routes are good for sort trips in a certain region or area, but when it comes to cross the country as I'm doing now, it's not the most convenient, unless you have plenty of weeks to do it... But in any case, in my way back heading south, I'll try to take some of these routes for certain places. Today I've been in "Cinder track", between Scarborough and Whitby, and it was really nice.
The thing now for me is to get something in paper, because not always is easy to have internet. So I'll pay attention to the recommendation by Olonerider. By the way, Olonerider, it can be nice to meet and chat for a while. I'm getting to New Castle Thursday at lunch time, and I'll be there at least until Saturday morning. I've no plans yet for next days. So tell me when are you up for a meeting.
Please PM me for my phone number.
[Edited to remove phone number by MODS]