You are right, Zambrano is meant for primary carer of a British citizen child or adult. What I meant to refer to was rather the Chen case law.

Hello, I am a third country national currently in the UK with my son of 6 years. My son is an EU national and holds an EU passport. I have only be living here in the UK for a few months and entered the Uk with a visitors visa. My son is currently in school and I wish to apply for a residence permit....