@Keef *******
I would say you are mostly correct. Things get a little more confusing with a multi entry visa but with a single entry visa, your visa is done the minute you walk up to immigration. What you get is a permit to stay stamp in your passport which can vary depending on the type of visa you had. The permit to stay can be extended to new permit to stay at immigration. It is obvious you understand the concepts, I am just trying to help a bit with terminology.