TeenHelp - coming out as trans at work?

so basically i'm going on work placement in france in two months. i'm going to be working with a small-ish company in the tourism industry as part of my university degree and, since i'm not officially out to my university and i haven't had my gender transition legally recognised yet, as far as my employer is considered i'm a cis male. this is an issue. being seen as female is very important to me as i was hoping to continue my transition while in france.

obviously at some stage i am going to have to discuss this with my employer. all i need to work out is when and how. i don't know whether to contact my employer now (via email most likely) and tell them about this, or to wait until i start work, go to my first day at work presenting male and see if i can get a chance to discuss it with them. i have never actually met anyone who works for the company in person as i was interviewed by phone and all other contact has happened through email, so i have no clue how they feel about trans people.

i'm pretty confused and it's very stressful as i was hoping that moving to france would be my moment to shine, but this is a major barrier. i'd appreciate any advice. ;-;