I'd say don't.
I trained as a teaching assistant, and am finding it really hard to get a job.
Alot of mums go in for this career, obviously because of the hours, getting school holidays off being the main one.
I don't like to sound negative, but to give you an inkling, I have met lots of women who are thinking or who have trained to do this (its easy as it is "just" a NVQ).
The last job I went for had over 170 applicants. For 1 vacancy.