How should I ask for a modification in the admision procedure of a Master programme? I am a Spanish student and I'm planning to do a Master abroad next year, concretely in France. I met all the requirements to get admitted into the Master but the procedure includes a final interview of all candidates in late June.

My problem is that in that time of the year I have my final exams and I have to defend my thesis to get my degree. I couldn't be able to travel to France for the interview then as it would conflict with my exams or the defence.

What would be the best way of asking to hold the interview in a different date (early June or July would work for me)? Would it be considered rude to ask if it is possible to held the interview via the internet (by Skype or similar)? I was thinking of sending an email to the responsible of the admission explaining the situation but I don't know if this is usual or it would be frowned upon.
Skype interviews are usual (e.g. I have one with Oxford). The school might prefer face-to-face interviews but there is nothing wrong in sending a polite (brief!) email.