Genealogy / Schnell / Robinson - Finding Polish Ancestry/Relatives [5]

Hello,

I could use some advice. My great-grandmother was named Herda Anna Dorothea Schnell and she married John Robinson (British). Herda came from a family of Germans living in Poland (allied, not axis) and they had a son Ralph Robinson in 1922. I now know that my grandfather lived in Poland until he was 11 years old and then fled to Palestine to escape the Hitler youth movement.

My question is, since the family lived in Gdansk (or Zoppot, Free City of Danzig) for so long, what records would still be avaliable today?

Thank you!