– (1) “Do you live in the UK?” / Alternative: “What is your occupation?” – (2) “How long do you stay?” – (3) “What do you do in the UK?” These are the questions I always get every time I cross any border anywhere except the border (on the way in) of my own country. I don't get this bit.
They aren't interested in the answer, they're interested in whether you have a ready answer and don't sound evasive.