I don't know whether you could term it a career, initially, but there is certainly potential for career progression from teacher to assessor to tutor.
I know teachers who do say 1 x 14 hour course (2 weekend days) @ £26 per hour per month and 1 x 16 hour course (8 x 2 hour evenings) every couple of months, making an approx total of £6500 income per annum.
There are different ways of working being developed by teachers e.g. some are doing work for Children's Centres, for NHS hospitals, for Health Centres. There is potential in these cases to do midweek work, perhaps.
However a quick trawl round mumsnet will always find parents upset because the only course they are being offered - even with say 4 months + notice is weekday daytime. Most parents want evenings or weekends, which is where it doesn't necessarily fit in with the teacher's family commitments.
If you progress to tutor, you can choose to hold tutorials on weekdays during school hours. However, your students will need to be observed and assessed from time to time and you will have to travel to wherever they are having their classes. My tutor lived 1-1.5 hours away from most of her students which involved her leaving home at around 5.30pm to observe a class starting at 7.30pm and when it finished at 9.30pm, she would drive home, then call me the next day to discuss feedback.
Having said that - I am an antenatal teacher and I love it. I'll just never be rich through it!