All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If you reside in a town where there are mosques or there is one mosque, then it is obligatory on you to attend Friday prayer even if you do not hear the Athaan (the call to the prayer). For more details, please refer to Fatwa: 88505.
As regards the excuses for which one can be absent from Friday prayer, the scholars have stated them in their books with the evidence from the Sunnah, and they are as follows: illness, heavy rain, fear of persecution or being beaten, or having no clothes to put on and other similar excuses which prevent the person from going to the mosque. As regards studies, they are not an excuse for not going for Friday prayer especially since you have stated that your friend can change the timing of the lesson in a way to be able to pray Friday prayer. But, if you reside in a town where there is no mosque, then you are not obliged to perform Friday prayer.
Allaah knows best.