No worries, let me know how you get on.
However that chapter is quite self contained. If you are getting NullReferenceException’s then the script for the MessagingManager isn’t active for some reason (which would explain why you aren’t getting the “Awake” console message)
I just whipped up a quick test using the code from the book and everything seemed to work as expected. I’ve packages it in to a .UnityPackage for you to try. (start a new project and do Asset | Import Package | Custom Package and select the file, then run)
You can download it here: https://www.dropbox.com/s/eg44gw9o8tb92mb/MessagingManagerAwakeTest.unitypackage?dl=0
Simon (Darkside) Jackson