If your son is statemented, the LA should name your choice of school provided that it's suitable for his needs and it's an efficient use of resources (i.e. there is not a cheaper suitable option).
Pinkorkid is right that the LA do not have to provide the 'best' education, but rather a 'suitable' one. But your right to name a school on his statement is very strong and the LA has to show that your choice is unsuitable/more costly rather than you showing them that your choice is the right one.
If they are both special schools, it's unlikely that one will cost more than the other unless the LA is including the cost of transport to the more distant school. You can, however, agree to cover transport costs to your preferred school, which will make the cost of both placements equal.
The other way to win your placement is to show that your preferred school is the only suitable school. I think you could show this in your situation as the schools are very different.
Access to a suitable peer group and to a suitable curriculum are both valid reasons why a school is suitable or not. The specialist status of the schools will be of lesser importance.
You need to get more information from both schools about their results. I wrote letters to both schools asking questions like:
- Breakdown of GCSE results and subjects (often this isn't available on the DSCF website as special schools have small cohorts so the results aren't published, be careful as some special schools do Entry Level GCSEs which are graded below standard GCSEs)
- Number of current students with AS
- No. of staff members with additional qualifications and experience in SEN/ASD
- GCSE options available (you may find the first school doesn't offer any GCSEs if many of their pupils are on P Levels)
- What ASD specific teaching strategies are employed at the school
- What are the destinations of school leavers from the school (college, work etc)
- What is the academic and cognitive profile of the students attending the school
- Copy of SEN policy, Admissions Policy, Curriculum Policy
You can ask these questions in person by visiting the school as well, but it's best to get it in writing as evidence.
You can also pull out quotes from Ofsted reports/their website/prospectus. The Ofsted will usually allude to levels of achievement by saying something like 'Records show that when students join X School their starting points are very much lower than those typical for their ages'. If your DS is achieving age-appropriate levels (or just below) then you can argue that he would not have an appropriate peer group with those students so he would not be able to progress in his social skills.
Does your DS have any recent assessment results to show his NC levels and has he seen an EP recently? We had an independent EP visit our choice of school and the school where the LA wanted my DS to go and he was able to write a report saying why the LA's choice wasn't suitable. Our choice was an indpendent school though, your LA may not fight your choice too much if both are LA special schools.
Just realised how long this post is, oops
. I went through a similar process last year (DS is Yr 7 now) so it's all very fresh in my mind!