Welcome to the forum GSB.
Yes if you turn off audio recording by pressing the button, or change it to off in the settings it will keep that setting, only a update of the firmware will need you to do it again as it is generally set to ON by default.
When you get the camera just set your time zone, do not bother with the time/date thing, that will be done automatic once the GPS get a fix and know your time zone.
Also in that regard dashcams, they do not change automatic for summer / winter time, so you will have to do that manual, and since you are in the UK it should be GMT 0 now and +1 when we change to summer time.
Really you can also just leave it at GMT 0 CUZ if you do have a event, there will probably not be any doubt about where and when it happen.
BUT ! as the little Garmin are a camera that need a APP to do changes to settings, it are easy to do so should not be a problem.
PS: Pressing the event button to save / lock a file, you might inadvertently press the microphone button as they can be pretty close on some systems.
But as i recall the Garmin say it out loud if microphone are on or off when you touch the button, so you will have to play the radio loud or be deaf to miss it i think.
A install hint.
Power the camera up and connect to it with the APP, this way you can use the live preview to make sure the camera are lined up correct, usually you can gauge that by looking at the bottom of the windscreen, and sideways if you have equally as much of the A pillars in view.
But as the little Garmin camera are on a ball joint mount you have a lot of flexibillity in that for adjustment, so your only concern should be to not mounting it too close to something that the wide angle lens might get in view ( like a sensor or something on your windscreen )
After that you can unplug the camera and do the routing of the wire, there are many guides on youtube how to route wires, it is generally the same for all dashcam systems and car make / models.
