Google TTS issue

Configuration
1

Hi team,

well, my first ever automation worked today - HA turned my garden sprinkler off after the test period of 1 minute!! ( high fives self :grin:) pushed it out to 10 minutes, then duplicated it for 1 hour on the orchard watering system. What a master!!:rofl:

However… now that I’m playing with automations, I thought I’d have a go at TTS announcements from my google home. I have a front gate sensor, which tells me if the front gate is open or closed. Its a sensor, that works via command line. - The sensor works fine in the overview page - I can see the sensor change from False to True when the gate opens. - I can also monitor it via the dashboard, and have a widget that both changes colour and MDI when the gate opens. However, try as i might, i cannot get the google TTS to work.
Ive tried numerous syntax / format combinations, copying items from the docs, the community and youtube to no avail. Tried data_template, various combinations from other users…

here is the current automations.yaml

- id: '1541053054723'
  alias: Veggie garden watering timer
  trigger:
  - entity_id: switch.veggie_dripper
    from: 'off'
    platform: state
    to: 'on'
  condition: []
  action:
  - delay: 00:10
  - alias: ''
    data:
      entity_id: switch.veggie_dripper
    service: switch.turn_off
    
    
- id: '1541057366386'
  alias: Orchard watering timer
  trigger:
  - entity_id: switch.orchard_dripper_
    from: 'off'
    platform: state
    to: 'on'
  condition: []
  action:
  - delay: 01:00
  - data:
      entity_id: switch.orchard_dripper_
    service: switch.turn_off
    
    
    
- id: '1541057939739'
  alias: Front gate alert
  trigger:
  - entity_id: sensor.gate_openclosed
    from: 'false'
    platform: state
    to: 'true'
  condition: []
  action:
  - service: tts.google_say
    data:
      entity_id: media_player.kitchen_main_speaker
      message: "The Front Gate has just been opened"

Some noob questions: - Does there need to be any other code in the config.yaml?
Does Google home ( in this case the kitchen main speaker ) need to be turned on first, via the automation in HA? - I note in the overview page, it is off, until I hit the power button to turn it to ‘Idle’…

thanks,

Jarrod.