@Sockwomble I personally would interpret the collection of the student by mum, as in the best interests of the child at that time. Also in the best interests of the other 25+ children in the class , waiting to start or continue with their lesson.
This topic is always very emotive and i do respect that. There can be many (8 -10 + ) SEN children in a primary Yr grp class at any one time, all requiring the support of a limited pool of TA's or HLTAs or BFL staff , who work across all year groups. Resources are limited at the best of times. These are not the best of times.
I can understand if you are the parent of an SEN child, this can be very very frustrating. I respect and acknowledge your frustration. Equally, parents of non SEN children are equally frustrated , when their child misses out on learning opportunities and lesson is disrupted, repeatedly. It is a difficult balance.
No parents frustration outweighs the other.
The OP should be allowed to work with the school and outside agencies, to obtain a diagnosis (and suitable funding /provision/alternative provision ) without all the hysteria surrounding this thread.
It looks like OP was called in to sch today/yesterday, behaviour discussed and has initially agreed to a part-time T/T. All will be documented and on student file, as needed for presentation to OFSTED. All part time T/Ts , reduced provision and alternative provision are scrutinised by OFSTED. A part time T/T cannot be "hidden" nor can registers and absence coding be amended.
I just feel a more measured response would help the OP and her DC and possibly other readers in a similar situation. We all share a common theme and that is that we all want the best for all our children.
Other peoples experiences are not the OP's and the OP should be encouraged to work in conjunction with her sch, LEA and other authorities at this time.