Thanks for your replies, I think the light bulb above my head is slowly sparking to life My first thought was that the above solution would be much more readable/elegant if written as below:
automation:
- id: timergaragelightsoff
alias: atoff
trigger:
platform: state
entity_id: switch.garage_interior_switch
to: 'on'
for:
minutes: 8
action:
- service: homeassistant.turn_off
entity_id: switch.garage_interior_switch
- id: garagedooropen
alias: "garage door opened"
trigger:
- platform: state
entity_id: sensor.garage_door_west_alarm_level
from: '255'
to: '0'
action:
- service: homeassistant.turn_on
entity_id: switch.garage_interior_switch
But that would give a problem if I manually switched on the light via say a wall switch. With your example I could cancel the timer to leave the lights on after switching them manually.