Walerzak. Help needed Trying to trace my father's roots in Poland

My father came to England after WW2 his name was Stefan Walerzak born 1922 or 1924 he has family in Poland the marriage to my English mum ended when I was 4 so don't know much about him and mum would not talk about him much so with not much information about him where do I start to trace his roots.

Betty

WALERZAK: originated as a patronymic nickname to indicate the son of Walery (Valerian).