Such a rollercoaster. I'm sorry to hear your update @Leafywool and that @Jimmyneutronsforehead it sounds like DS is in distress at drop off. On transport you're currently comparing a known with an unknown which is not really a fair "fight". There is something to be said for giving it a go. Regular in person contact with school has value especially in the early days, but doesn't need to be 10x per week.
@Leafywool I don't know if this is specific to our LA so maybe not much help but here reduced timetables can only be agreed for 6 weeks at a time. DS had one for over a year so it was a series of multiple 6 week arrangements. Obviously not Plan A and I think there is a good case that if they need a PT timetable long term then they are in a settings that is not meeting their needs. For DS he was Y10/11 and we all agreed the setting could not meet need, but he was in no state to cope with another move and staying there through GCSE years with a reduced timetable was the best option. But your DD is younger so would it be the right thing to reduce timetable long term? There's an argument that if she is too distressed to do FT by Christmas maybe the setting is not able to meet her needs, and her time this year would be better used getting her into a more suitable setting. (I know, I know)
I wonder if school SEN team could help supply any structured resources to help autistic students identify what the problems are. We once (in desperation) wrote DS a big questionnaire to help elucidate what might help. One bit I remember was 15 possible problems he might have with one of his subjects. We asked him to rank the most bothersome of our ideas and also identify which ones were not a problem at all. The options were sentence starters too so we got some more insights from him talking round the list.
We included some mentions of his special interest, some silly ones to keep it light, some things he would be too polite to say such I don't understand Mr S's accent. We did similar across different aspects of the school day to get an overall picture. Open questions would have been better for most students but he really struggles with pragmatics.
Another useful thing it brought out was where something was a problem, but only a small one, sometimes he'd rather live with it than deal with another change. This was valuable insight which moved some things from being negatives outside of his control - very dysregulating - to negatives he was choosing to keep in a sense and had a sense of ownership over which made them slightly more tolerable.
What if didn't do was address how hard it is sometimes for a child or YP to identify what is so distressing.
Not sure if that is much help when the meeting is tomorrow @Leafywool . For DS I think I'd be asking about access to the RP and quiet time through the school day but appreciate DD will want to be with her friends. Is it possible she is just not up to being "on" all day including breaks and lunches? But breaks and lunches are critical for her settling in so what else can give? Is there another subject that could be dropped for her to have some downtime without missing her social time? See if there are any RP outreach groups or things she could be invited to there without being a fully paid up member. She is showing so much grit going back but she needs an environment she can cope with or the wheels will come off again.