@sozobe,
Not much to add to what others have already said, soz.
But I do want to wish you all the very best with your book. Good luck & good on you for having a go!
As to first or third person character-driven narrative ... I'm easy. It depends so much on the story. Which works best with that particularly story.
And it doesn't have to be
just one or the other .... I've read quite a few rivetting novels where the perspective of different characters is explored during different parts of the story, in a variety of ways ... like via letters, their own "voices", etc . I can also recall one example (
The French Lieutenant's Woman), where the author (John Fowles) speaks directly to his readers about the frustrations he'd encountered in writing a "suitable" ending .... so he ended up providing us with
two, so we could choose our own!
How much use this might or might not be to you, I have no idea. But just saying, feel free to be flexible,
if that seems appropriate at some stages of the storyline. No need to stick to only first or third voice, unless that suits best.
Good luck & keep us posted. I'll be really interested to see how this goes!