Do you guys know if my employer is required to pay me redundancy payment for this? If I don't resign but I have to leave, will I receive the statutory redundancy payment?
Wow. I am so sorry you are going through this.
Two perspectives: immigration law vs employment law.
Immigration law:
option 1: your current employer renews their license and then you reapply for your visa, following the normal procedure (CoS, though you are probably exempt from the RLMT).
option 2: find new employer who runs the RLMT and issue you a CoS and then you pply for a visa.
Failing both of these, you will not be eligible to apply for a new Tier 2 from out of country until you have served the 12 month cooling off period.
Employment law:
Completely separate from immigration law. They could argue that by having no right to work in the UK, they cannot employ you and have no choice but to dismiss you because of your immigration status. They have treated you APPALLINGLY by not telling you about this. I suggest you get a good employment lawyer with some knowledge of the immigration system to sort out redundancy if your current employer is not willing to go with immigration option 1. I am unsure if your employment rights supersede your immigration status/ rights.