In the UK a University degree is 3 years, even teaching, so 21 is possible. But given this womans surroundings I think she was only a teaching assistant for special ed kids, which can only take 1-2 years in our equiv of community college.
I agree as i'm sure you need a PGCE to teach unless it's in a private school. Scotland has different laws to England but assistant or placement year is most likely.
What a horrible story. No-one comes out of this well