The weather has broken! I had to wait for the rain to finish before I could assemble the completed antenna mount complete with dish, and test the motors.
Now the basic structure is built, I can add the motor drives. I worked out the required turning rates to track low Earth orbit satellites (though that is not the prime purpose of this drive). Geared motors were bought on Ebay from China to suit this, along with toothed drive belt and drive belt pulleys designed for 3-D printers.