It's a great job? I started after a different ( mental health) career in the NHS, years as a sahm, and a year and a half volunteering. No further quals although I am thinking about becoming a HLTA.
I will just say one thing about working in the school your child attends.
It can be entirely unproblematic, especially if your child is an absolute angel (!) but I'd set some clear boundaries for yourself, other staff and children from the off. I would stronlgy recommend trying not to be in your DDs class
In school you are know as your name, not Xs mum
If a child tells you something negative about your child at school, tell them to tell another member of staff
Don't have discussions about your child with other staff during the school day, unless urgent.
Ask them not to talk to you about stuff that they wouldn't deem necessary to report to another parent.
Be prepared for other parents to try and winkle information out of you about the school, other staff or children
Apols if this is teaching grandmother to suck eggs!
One of my DCs liked me being there. The other felt his style was being cramped, and that I would find out about small things that would happen in the course of a day that I would neverr had heard about otherwise. I do think it is important to be sensitive about that for their sake.