Curious why “making him leave at 16” is an option higher up the list than “stop driving him to his fun activities” 🤣
I’m sympathetic, but having got it out of your system on here - calm down.
The money is gone. You have to pay spring term anyway and are you already too late for a term’s notice for summer term? Not that I think you should pull him out anyway - but it doesn’t even make sense on the money.
Firstly, let him fail his mocks - if he even does. It’s a thing. It’s partly why they do mocks! For some kids, it’s what focuses them - that bad result.
You can even “let” him fail his whole exam. You might in the long run find that’s more productive.
Stop talking about “we” are not doing A levels. Next steps are his choice.
He’s had a couple of years in a private school - there’s every chance he’ll get the magic 4 for English Language & Maths. You can get a low pass at GCSE maths with only KS3 knowledge. How has he been doing so far?
I would take the approach of telling that you want him to study and you’re here to help if he wants you to. Separately, ask school how he is performing. Sit back and see that the impact of mocks is. Make sure he knows that private for sixth isn’t financially viable. That might actually be part of the problem - is he surrounded by kids motivated to do well, or they can’t stay on? If he knows he can’t, he won’t have their motivation. There’s a common exit to state at Y12, but not from all schools. Stop talking about GCSEs all the time, and encourage him to look at college courses. Sit back and let him look - don’t hammer home that he needs to pass GCSEs to do those courses - he knows. Let him realise that quietly, don’t back him into a corner. But let him get interested in the KS5 courses.
Separate all his GCSE study stuff and your overstretching your finances from general behaviour management. Like - no to driving him around if he’s not polite. And not washing his clothes for him.