All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If it is not possible for you to attend the Jumu'ah prayer except in a way that would cause you some harm, then it is lawful for you to miss it and pray Thuhr instead.
As for Thuhr you have the choice to pray it at the beginning of its fixed time, in the middle, or in the last period of its fixed time. But if you can pray Thuhr in its best time; i.e., right after the Imam leading the Friday prayer stands up from the second Rak'ah, then that would be better and more appropriate. But if delaying the prayer can lead to missing praying it at its fixed time, then it is more appropriate to pray it at its early time. Know that it is unlawful for you to delay the prayer from its fixed time. In fact, you should pray it at its fixed time if you can.
Allah knows best.