The date is 1 April 1980.
Spots should go off when you dip the headlights - using the same switch. Easily done, just use a relay operated from the main beam, via your spotlight switch.
I'm pretty sure a single front fog should be mounted on the driver's side. There are rules about how far it should be from the vehicle edge, they'll be on the web.
They are: Regulation 20, schedule 6 of The Road Vehicles Lighting Regulations 1989
In short, if you only have 1 fog you can put it anywhere but you must also use dipped beam. If you have a pair you can use them in place of the headlights, but they must be within 40cm of the vehicle edge and within 120cm of the ground, not a huge restriction on a Mini