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.
Friday prayer is a very serious matter. It has many virtues. Leaving it without any legal excuse is a great sin. The Prophet said: “Those who are not attending the Friday prayer should change their ways; otherwise, Allah, The Exalted, will seal their hearts and they will be reckoned as the heedless” [Muslim and others].
It is reported in al-Musnad and in the books of Sunan that the Prophet said: “Whoever misses three consecutive Friday prayers out of negligence will have a seal put over his heart by Allah”.
There are many other sound Hadeeth that urge performing Friday prayer such as the Hadeeth related by Imam Muslim that the Prophet said: “The five prayers, the Friday prayers from one Friday prayer to the next Friday prayer and fasting in the month of Ramadan; from one Ramadan to the next Ramadan is an expiation if major sins are not committed”.
Furthermore, the Saying of Allah is sufficient in this concern; Allah Says (what means): {O you who believe (Muslims)! When the call is proclaimed for the Salat (prayer) on the day of Friday (Jumu'ah prayer), come to the remembrance of Allah [Jumu'ah religious talk (Khutbah) and Salat (prayer)] and leave off business (and every other thing), that is better for you if you did but know!} [Quran 62: 9].
Therefore, everyone who is obliged to perform Friday prayer (mandatory on him) should keep doing it in the mosque. One should avoid neglecting it except for a legal excuse.
Know that basically Jumu'ah prayers should not be performed in many places except if there is any necessity. So, you should perform Jumu'ah in any mosque that is near to you. If the authorities do not permit you to do so, you should give up working there and should seek another job. If you are in need of this work then you may perform Jumu'ah in that place during the period you are seeking another job.
However, Muslim scholars have different opinions concerning the numbers of Muslims for the validity of Jumu'ah prayer. The preponderant opinion is that three persons including Imam are sufficient for performing Jumu'ah prayer.
Allah knows best.