The charity ‘Contact’ have a comprehensive directory of medical conditions and learning disabilities, with details of organisations which can provide support for each type. We recommend starting there!
We have listed below other advice organisations (whether on SEN or other topics) and details of how parents can contact professionals such as educational psychologists or speech and language therapists.
Advice line advisers should always check whether the parent/carer has accessed support from their local Information, Advice and Support Service. IAS services are able to help parents review EHC plans, and attend meetings with schools or local authorities (depending on service capacity): https://councilfordisabledchildren.org.uk/information-advice-and-support-services-network/find-your-local-ias-service
For further support with SEN issues (for example, if the parent says they are struggling to get an IPSEA appointment), they can try:
For children or young people who need advice directly, Just for Kids Law provides legal advice and advocacy services - http://justforkidslaw.org/contact-us/referral-form/
If a parent wishes to privately instruct a solicitor (i.e. not through legal aid), we would not recommend a specific firm but would advise that they need someone with expertise in education law. They can search for education solicitors in their area using the Law Society pro-search function: http://solicitors.lawsociety.org.uk/?Pro=True