Hi, have you considered a specialist school instead of a main stream one?
Secondary school SEN funding is very limited and unless you have an EHCP already, the school is not obliged to offer you any support. Some schools will, but this is minimal for the complexity of needs you are listing and where your child is academically.
It does sounds as a specialist centre might be a good option for your child.
Please be aware that unless you have a SEN solicitor, the process will take around a year and half and although your child seems to have a number of SEN, you haven't mentioned any self care or medical/health needs, which you will need in order to meet the EHCP triangle.
Three River's has an amazing caring SENCo, and they do go far and beyond to help the students.
Esher High, is not best known for their SENCo provision without an EHCP
Thamesmead - sorry, I have no knowledge of this one
Cobham Free School - Has too many SEN children in their register, so I would imagine their resources outside their EHCP funding is very limited..
Salesisan and HInchely Wood, they both have a SEN unity, if your current primary school is supportive, I would get the SENCo to liaise with them and see if they can help you visit and make a decision if this is the best way forward.
Once again, please be very aware that the level of support a SEN child receives, I would imagine your child is now tier 1 with possible several SEN codes attached, in a secondary school decreases lots without an EHCP attached.
Best on your way forward