Hi,

HT - High Tension, its the high voltage lead that runs from the centre of the coil to the distibutor. Unplug it from the distributor and connect it to earth to stop the car starting. Alternatively you can disconnect the connector from the trigger points for the same result, its a big connector block on the left of the distributor with a wire that goes down to the lower part of the distributor.
Yes, if the CSV is turned on for a short time after start a cold engine then the thermo-time switch is working.