Hey mate,
Yeah you don't really need to be that tech literate to be honest to use Kodi; I will say one thing, you won't get the same reliability from Kodi addons as you will with official cable or satellite TV; I'd recommend trying it on your laptop just to see what you think
To be honest the shield TV is massively overkill if you'll just be watching BBC, ITV and sport; the shield TV is really for what I'd class as a power user
The Nexus media player is fantastic for easy installation, the fire TV is also a great box; it's difficult to pick between the two to be honest bud. A lot of bluemooners here seem to use the fire TV so you might get better support with that box :)