In answer to the OP...
I was on a carers break from my job when I started volunteering, so had plenty of time. I was helping out in my daughters class initially. I'm not pushy, not cliquey, not really interested in doing anything but helping the school. God knows, they've done plenty to help me and my dd.
In reception I heard readers, sharpened pencils (which amused DH no end...after all my management roles - spending my afternoons doing stuff like that made him giggle. I loved it), filed papers, etc. I always helped out at school trips, volunteered for fetes, craft fairs, etc.
I then did a reading mentors course and supported a couple of Y6 children who were struggling with literacy and did that for just over 2 years.
That sparked my interest in education and now I've quit my old job and am working at the school on a supply basis (ie temping effectively) as a classroom assistant. I still do the volunteer reading and attend school trips when required, but I also assist in all classes with numeracy and literacy. I'm retraining and loving it all.
It didn't start out as an alternative to my old career, but it looks like it's been the trigger for it. Retrospectively it might look like I've engineered a niche for myself in the school, but I've always said I'd do the same as I do now even if it was unpaid, because I love helping the kids who are struggling the most.