Hi, I think your question is a GDPR/data protection one. As I understand it, if parents have not given consent for you to share this information with the new school ( particularly as it is sensitive information like SEN status or medical diagnosis) then I don’t think you are allowed to.
Your school should have someone who is responsible for data protection who should be able to advise you. Failing that you should be able to obtain advice/support from someone in your local authority/academy Trust who knows data protection law.