Can't download apps from App Store as get button doesn't start download
From the Apple help site at: https://support.apple.com/en-us/HT201400 it recommended 


  Make sure that your date, time, and time zone are correct. Tap
  Settings > General > Date &amp; Time.


My settings were correct. However I turned off the automatic date/time/timezone feature to make the date and time zone setting be manual.

Voila, I could connect to the iTunes/App store. I had turned my phone off and on several times. I really wanted to avoid doing a reset. So I've escaped it for now.