I would think the most accessible editor for Python will be a toss-up between textMate and Visual Studio Code.
The main thing you have to be aware of in either editor is the fact that VoiceOver doesn't really natively support reporting line indentation, so unless you are using braille, you will have trouble doing this.
Python relies on indentation to indicate various things in the code, so you'll need some way to fix this.
In VS Code, there's an extension developed by a blind person that does this:
$1For other editors , there is a really recent project created by two blind developers that does a similar things for mac-wide:
$1​
As for accessible ways to learn it, really any text-based tutorial that pertains to Python 3, which should be anything relatively recent, should work just fine.
Learn Python the Hard Way comes to mind, but NoStarchPress has a bunch of python books as well that are perfectly usable.