that's useful info, thanks so much, yeah we have had the b^^cks about we are fluent, you must trust us, we are the professionals etc etc, from the school with the unit that we hoped he would go to, (coupled with we won't learn the signs he uses, won't check for differences between signalong that Ed use and SSE that ds uses, and won't seek to expnad his vocab), he'll go to that school over my dead body!!!!! 
Found a local ms that were really positive, "oh we would need to train a TA, so they were ahead of him, well really we will train two incase one was off, and we whould train dinner staff too, and others he will come into contact with," could have hugged them. They already have two deaf (implanted) TAs and run a signing group as an activity for the kids. (will be angling for one of those TAs for ds).
We had discussions about what level of signing qualification was needed, the LA do signalong, but that is more single words... even tho there is lots of vocab overlap, but I will be making sure that they are ahead of him, (cue scary mummy!) 
The local speech and lang units wouldn't take him because of his LD. and the local SN school which has good rep re ASD is so 'PECS rules, signing does not work for ASD kids' that he would not fit there... 
So glad your ds has found a school that suits him.