How could the Brits/Chamberlain (or anyone) not know the anti-Jewish laws that had been and were being passed?
Be fair, most European states at the time had some kind of anti-Jewish laws, albeit not as stringent as the Nazis, but up until Krystallnacht it didn’t arouse a lot of disdain.
The Holocaust came later. Most of the victims were Eastern Jews, most German Jews managed to get out. England was not willing to go to war in 1938 to keep Germany from mistreating its Jews. Neither was America, France, Switzerland, Sweden, Canada, Cuba, ....