When searching for English translations of books or essays by a famous French author, do a search where you specify the author's name as an AUTHOR and the word English in the TITLE.
You are unlikely to find French newspaper articles in translation, but you may find English language news articles that cite articles from French news sources.
Gallica is the online library of the French National Library, with over 6 million documents online. Most finding aids are in French, so if you don't know much/any French, it will be best to search it for the French term for "interwar," L'entre-deux-guerres, names of places, people, individual years, or regimes (e.g., Vichy).