i think the time and energy YOU would have to put into, researching how to get an apprenticeship, COULD be done. But you might not complete or pass your own studies this year, as a result.

it is time to choose.

when you get home from full on prac, exhausted, looking after your household and your girls, and doing your coursework, you already have
- unco-operative X to deal with
this new stuff would be adding
- 17 to check and remind and argue with about cleaning up after himself
- 17 to check with and remind about chasing up apprenticeships, gettign him ready for interviews, taking him to see contacts
heaps more that you will know about, but i don't, cos i'm not there (does he take responsibility for his own meals, his own washing, will you have to buy his clothing needed for apprenticeship - it all takes time and energy.

I realise it's hard to say no to your mum, with how she has helped you of late. You are in a tight spot (what is new, i know).