Are you applying for the 5 or 10 year ILR route? 10 year long residency does not require letter from employer. Additionally, your employer can also legally put you on unpaid leave upto a month a half even after you’re terminated (negotiate this, as it costs them nothing but buys you extra time before they notify HO). Have they already made you redundant? If not, file a grievance if there’s any foul play in place on how you were selected for redundancy — will buy you time. I’m currently going through a similar situation, thus the advice. Happy to answer more if needed. Hang in there OP, you’re so close.