As I can pull the dashboard knob with the fiery flames symbol fully out of the dash with it's inner-wire attached I think it might be safe to assume that there is no heating available.
Especially as when looking on the cylinder head where I expected a control-valve and heater tubing to be there is a vacant space. Why? You only have to sit in the car and take 2 deep breaths in and out and all the windows fog up for goodness sake. How on earth are Clarissa and I going to successfully go dogging in this?
Some of those magnetic squeegees they use on fish tanks?
Many a Mini got a heart transplant from a Metro donor back in the day. They had no water valve, diverting the airflow instead to control temperature. It was a while before the later Minis adopted the same thermostat sandwich plate plumbing with the addition of the remote water valve.
You could drill the requisite hole(s) in the head for a valve there, or acquire the bits to add late model heater plumbing. It's worth noting the early set up used 1/2 inch hose while the latter was 5/8". You can mix 'n match, if you have to.
