Oh OP, how scary and frightening for you.
Has he an EHCP at all? I'm assuming that he hasn't, or it would have named a school? If not, starting the application process yourself - IPSEA will help you - is always worth it. Nothing to lose, and everything to gain. If he has identified needs, so may require an EHCP, then they have to assess, and that means their own experts will conduct proper assessments for him. If you're home educating, it can be the best means of securing proper assessment, never mind provision, because it means the ed psych, SALT etc will see him. Schools tend to gatekeep (for, sadly, wholly understandable costs reasons) and many kids in dire need are just never seen by these professional services at all.
Please don't panic. I'd contact your local Home Education team - all LAs have them - and talk through what the hell is going on. It's a postcode lottery, but ours is brilliant and they really support home edders, especially if SEN is in play as they are painfully aware, from their role in schools, of the mess provision is currently in.
Look on Facebook for your town's home ed group, and then look for the county one. You'll find a wealth of expertise, including legal, from fellow home edders, and massive support. I think well over half the kids now home educated are disabled, mostly on the autistic spectrum, because schools are catastrophic for them in so many cases. You won't be alone, I promise.
You can also get help from the main home ed charity, Education Otherwise.
Finally, I would go and see your MP. It's amazing how fast Local Authorities can become efficient, when they have questions asked of them by someone more powerful. Home education is your legal right, and losing the paperwork and then having you arrested isn't a good look.
Don't be afraid. Judges don't work for the local authority, should worst come to worst, and your child is in home education after a school placement broke down, while you await a better one. That's not failing to ensure an education. You've broken no laws. You just want your son to get an education that meets his needs, which makes you a decent parent.