While the employer policy might not have the traditional "2 weeks", it's still worthwhile to give an advance notice.
Talk to your superior about how you are feeling. Let them know that it might be a case where you cannot hold out until December.
It's not like it can be any more damaging than leaving "gracefully" without any heads up whatsoever. you would be at the very least letting them know that they'll need a replacement.
Secondly, "good terms" is open to interpretation. I'm on good terms with my managers, but ultimately I loathe the company we work for and if asked I would honestly tell criminals to take another crack at being a criminal before working for this company.
I have spoken to some of my superiors to be references for me and they've kindly agreed. However I have not requested an official reference from the company, and won't do that until I know how I will be leaving (if I give any official notice of leave, for example).
I'd imagine that your employer has a hierarchy still, and that your boss isn't the head of the business. It might very well be that your boss completely understands your position, or has been in it before even, and will help you out if they like you.
And that is why it is worth talking to them.
If you were happier then, and you have savings, you know damn well how quitting might play out,
Like another said, it's worth putting a resume on an employment site just to see where you get.
You have experience and qualifications, and while you might not want to teach per-se, should you find yourself in a field you do like - that experience teaching could mean an employer will see that you could be a valuable asset in training new employees in your field.
Take it from someone who has nowhere near the amount of employability you have, you honestly look good enough to hire. Even if you do have gaps.