Hi, we have a very similar set up, mainstream secondary, ASC unit where students are also required to be able to manage at least 80% of time in main school.
We very often receive plans where it is very clear that they will struggle to manage in our setting and I do send in a response stating this.
I go through the provision and list everything they need or struggle with and why they will not manage in our setting.
It doesn’t always work though and we have been directed to take on. I k is you are on holiday now but I do respond to these as the 15 days turnaround does not take into account school holidays or weekend. Or at least it doesn’t in our LA.