@Mickyboy All I do is switch to 'Away' mode.
I don't know when you last checked or updated but this function "turn off all heating" has now been present for some time.
If you have a wired thermostat you will need to bridge this out and set up the thermostat with wireless control and set it to call heat from the new extension kit to control heat.
You will then need to setup all your TRV's to call heat from the new extension kit and not the wired thermostat which is what it would have been set for before you installed a extension kit. This can be done in setup.
Heat cannot be called from both the wired thermostat and the extension kit. the extension kit has to do all the work.
Tado extension kit cannot turn on the boiler due to the fact that the wired thermostat may be off.
Each thermostat and TRV has to be setup with the correct zone controller.
Hope this helps