There is an academic article in English on this topic: Rose Holmes (2018) Love, labour, loss: women, refugees and the servant crisis in Britain, 1933–1939, Women's History Review, 27:2, 288-309. The citations would indicate which archives where the author found documents. We do not subscribe to this journal so I cannot send you the article. Ask your local library if they can get it for you.
If you read German Traude Bollauf wrote a book on German/Austrian Jews who went to England to work as domestics: Dienstmädchen-Emigration: die Flucht jüdischer Frauen aus Österreich und Deutschland nach England 1938/39 (2010).
Oral histories are another option. The United States Holocaust Memorial Museum has thousands you can listen to from home via our Collections Search catalog https://collections.ushmm.org.