Bringing together information from Starlight's several posts, I believe the following may be the case (correct me if I'm wrong, Starlight):
When in mainstream, SL's DS, who is in Year 2 and has ASD, was in top groups academically but there was a concern that he would need support when tasks required more inference than literal thinking.
He therefore moved to his current school - a SALT school - for additional support in these areas. Since then, his academic levels have been reported as far below expected levels for his age, using b-squared assessments, but the school is reluctant to share these assessments with the OP.
SL is exploring HE or flexischooling as a route to boosting his academic performance rapidly (by the end of Y2) such that he can return to mainstream. She already does considerable work with her DS at home, but is frustrated that work done at home on e.g. handwriting is not reflected in work done in-school, and fears this may be limiting the schools' assessment of his ability.
My feeling, FWIW, is that the first step would be a full and open sharing between the OP and the school, with the OP taking in all work done at home (including videos of e.g. reading or other skills that do not involve written recording) and having an open discussion about assessment and the way forward. But that is just my opinion.