Edinburgh to Portsmouth (basic touring questions)

[CooperS]

As a prelude to my end to end attempt next year I want cycle Edinburgh to Portsmouth (live in two places so makes sense) over a long weekend (455 miles over 4 days).

Now I haven’t even started planning for next year so excuse the basic question but I’ve put in the route into Google maps and said no motorways but obviously it then takes you down A roads.

Is this what others do when touring? Or are they best avoided and then which tool do people use to not got through this process manually but getting an old fashioned map out?

[itsnotarace]

I would personally use something like http://www.bikeroutetoaster.com/Course.aspx or http://ridewithgps.com to map out the route in detail avoiding main roads. Both of those will produce elevation charts as well so you can avoid the bigger hills if you wish.