WALES IDP not being adhered to for teenage son - push for post 16 extended home tutoring?

Hi - new to this and looking for advice please, particularly from anyone in WALES that knows about our IDPs. 

My 15 year old son, diagnosed autistic with demand avoidant profile and additional OCD has been without education since April. He has an IDP as we're in Wales.  Mainstream and specialist settings failed and after 16 months home tutoring, she abruptly left. Nothing has been in place since, with no plan to move forward in September which could be his final year. He's started no qualifications and is already a year behind peers or further because he's not done any exams due to the messing around with his education over many years. 
My query is, am I able to push for Education POST 16 at home, (or a library if he can be persuaded) provided by the LA because he's so far behind his peer groups. With his demand avoidance and OCD being challenges to his learning, he clearly needs more time than others. He's only done snippets of work at GCSE level and started no specific qualifications. While his peers from mainstream are getting their GCSE results, he's not even started or obviously done any. He wouldnt be ready for work at 16 due to his demand avoidance and OCD standing in the way and likelihood of no qualifications by next year and further education colleges would not be equipped to support him (I work in one so know). 
Im in the middle of a complaint regarding things uncovered in a SAR that are discriminatory so do I request for education to be extended in the home with a tutor in the complaint and hope they agree? or do i just have to go to tribunal to get something set in stone? My son is very stressed that so far, nothing is happening since the tutor left. 
Many thanks,