I second the suggestion that you simply take him in at 9 am and leave him till pickup. Email the SEN caseworker, pointing out that the staged start is now over and he is entitled to a full time placement.
I would also point out that if a part time placement continues past the staged start, then that means that a day setting is insufficient, and that he is therefore now in need of a highly specialist residential placement somewhere such as Breckenbrough. Because he is entitled to a full time education, and if they can't give him one at this school, why, they may need to reflect upon what that means.
They want you to home ed, yes. But they can't make you home ed, and right now they're just not bothering to address this because it's a problem for you, not them. So I'd highlight that there's potential for it to explode into a huge problem for them, financially, if they provide you with a stack of evidence that needs cannot be met at all, locally. Give them an incentive to make this work.
I also suspect that they want it part time as long as possible because that way, they save the school transport costs. The school and the LA both gain from this arrangement. But if this placement fails, residential is the next step, and that will hugely increase their costs. Create a paper trail making that case. Get the SEN caseworker to stop ignoring this as someone else's problem, because if this goes to Tribunal and there is no full time ed on offer they can't defend a residential, and they know it.
SOSSEN are brilliant. I'm a bit biased as I know one of the staffers and she is a rock star.
My own LA tried to argue that my child, who is academically extremely able, should go to a purely vocational school. No prospect of GCSEs, not ever. Functional Skills in maths and English, and that would be it. Otherwise he'd learn bricklaying and carpentry. He was 9 years old at the time. So a clever child would lose any chance at all of anything but manual labour, before he was even in double figures. Wasn't specialist to his disability in any way, in fact they mainly cater to kids who've been excluded. Mostly teenagers. No therapies for his physical challenges at all. Those physical challenges also meant that he couldn't engage with the vocational curriculum, anyway. We assumed they did that to try to scare us into keeping him in mainstream, where he wasn't coping. Just to save cash. So we borrowed a huge chunk of money, and spent it getting him a place in a school where he could access an education. Which he is entitled to have.
We were lucky enough to able to borrow - BORROW - twenty thousand pounds, just to piss up the wall forcing the LA to do what the law said they should have from the start. To anyone unfamiliar with SEN in this country by now, I'm not even joking. That does count as lucky. I know someone whose breast cancer meant the GP got referrals for her kid, and that's the only reason she got an EHCP, because school were dismissive of problems but each new medical report was more serious than the last. She's chuffed she got cancer because it means her kid got what she needed. How many levels of fucked up is that?
It's a hidden world, SEN provision, isn't it. One where 95% of parents win their Tribunal cases, but most can't afford to get to Tribunal at all. So all too often, their kids are failed. We all know EHCPs are deliberately being written so they can't be enforced, and lots of parents don't know that because they don't know how they are meant to be designed. Lots of weaselly descriptions of provision without saying who gives it, how often, or for how long, so ten minutes a month could be all they get when they need two hours a week. A dozen hours with a TA, but that TA can be the normal one in with the class, not 1:1 at all, and the child gets no more time with them than anyone else without an EHCP would, and the parents only find that out when they ask WTF. The whole thing is some horrible game. It's beyond shit, and I know how you feel. I send so much solidarity and sympathy and support.
Try SOSSEN. Honestly, do. They do answer their phones and they can be such a comfort.
The system is so much more broken than most people could begin to imagine. It all happens in the shadows, and most people never engage with it, so there's little incentive to fund properly or get things right. And when you look at the mess the NHS and mainstream education are in, it give you some idea of how dire a hidden system, used by children whose parents are mostly too drained to do more than fight for their own child, has become.
It's fucking awful. I send love, solidarity, and virtual gin.
If you'd like a vent, PM me. I'm using a different user as I don't want our LA to link to my usual one (people will think that's paranoid. Bless their hearts, and try googling Connor Sparrowhawk, aka Laughing Boy) and I would absolutely be happy to chat. Keep on keeping on. Your son is enormously lucky to have you as his advocate. If only all kids were so blessed.