oh, it was a situation which really saddened me - wasn't that back when your ds was looking forward to school? and then he arrived, and his desk was moved apart.
Glad oyu've written the letter. you could always add a "We await a response within 7 days, with a plan as to how to move forward form here" as otherwise you could wait around for ever...
I do hope you can get htis sorted.
wrt your other school choices - how likely is your ds to get a place at these schools?
if it is likely, and just a case of moving him and sorting out the school run clashes, then I would say do it, if you are reasonably sure he will be treated better.
the likely outcome of any assesment is that you want him to move schools anyway, so you could just move him now.
my point re: keping him in school was instead of home schooling.
if he is going to be moved to a school who are likely to be more proactive, and more supportive when it comes to statementing, then the move can not ocme soon enough, imo (we did that with dd1 - gave up on hopeless LEA who were not listening, and moved her to another pre-school (in another LEA) virtually overnight. it was still a batle after that to get her statement, but we got there in the end.