I have just moded the heater on my TD4 , home made and cost about £30 I used a programmable thermostat from screwfix that I added a resistor to make it think it was 15deg hotter than it was ! this programs the heater to come on for 15min min at below 5 every AM weekdays as programme timed, also have a press switch connected to rear screen timed relay (adjusted to 15 min ) so I can one shot the heater any time.
I have made the fan heater work at slow speed to get the heat out of the heater to de frost without going to the car in the AM
I was toying with a remote for £30 from Maplins or CPC but cant see the need at the moment
Gordon