CNC - how does it work??

[JAZZCNC]

Another question I have, is about how people who don't have industrial work units usually house these machines? Would you say a purpose built "shed" in the garden would be suitable for something like this or are these types of machines better suited to a heated/climate controlled work area?

Nothing special is required other than it's dry. I have installed literally dozens of machines in standard 8 x 4 Garden sheds and twice as many in purpose-built sheds.
If the building is damp then a dehumidifier would be recommended if the machine is stood for any length of time.

Finally, if a well built shed is capable of housing a CNC machine, what sort of shed size would you need to house say, a 1x1m machine which would allow you ample size to move around and operate the machine safely?

Only you can really decide how much access you want around the machine, but at a minimum, you only really need to access the front so, in theory, you could have a shed 1.1mtr x 2mtr and still access the machine safely.
Often in confined spaces then the machine will go in a corner and you would access it from the front and one side but this does depend slightly on machine design. For instance, the JZR machines I build have relatively high sides which limit access from the sides, so they are mostly accessed from the front or rear but mostly the front. The one in the picture below was in a steel container that was under 2mtr wide and as you can see mostly accessed from the front.