Great link, thanks steelgoose. The rpi's are fantastic devices.
I have a rpi3B on my sound system/tv running osmc and kodi for my entertainment system. I love it.
Being a long time linux user I am already quite comfortable with the OS and before I set it up as a entertainment system, I often used it as a headless machine to run 3d printer tasks or cnc GRBL server. I must get another one to replace it.
The zero-w will probably become easier to get at a reasonable price as manufacturing catches up with demand.
An rpi on the gate controller would be great. I could connect a camera and take an image of the registration of every vehicle/person who went through. Overkill again as I don't have a problem with theft out here.
Thanks again for your reply.