What is Marek Lange’s secret?

This is what I know:
Marek Lange.
Born: 1923.
Place of birth: Litva, Poland. (NB no record ‘Litva’. Search Russian archives?)
Father: Stanislau Lange
Mother: Kristina Lange.
Arrived in UK 1943. Joined Polish Free Forces. (What was Lange doing between 1940-1943? How did he survive the Nazi occupation?)
Marital history: married 1955, divorced, 1961. Ex-wife died, 1963
Children: Katya Lange, born 1959

Any info on KURAPATY FOREST or COLLABORATORS in Eastern Europe during the Nazi Occupation gratefully received…