I don't know how much English skills you have now, but not all people who have passed EIKEN Grade Pre-1 or 800 score on TOEIC L&R can get these part time jobs you mentioned here. There are a lot of people who cannot speak or write good English even though they have actually have passed EIKEN Grade Pre-1 or 800 score on TOEIC L&R. This is a harsh reality. On the other hand, there are people who get a better part time job using English even though they don't have any English qualification. That depends all on yourself. I work for a law firm dealing mainly with overseas matters using English to communicate with attorneys at law in the US. What do you think of my idea? Answer in English now.