Transferring indefinite leave to remain stamp to biometric card

I am trying to start working for NHS but has been told I need to transfer my Indefinite Leave to Remain stamp from the expired passport to Biometric Residence Card. So I need to do this ASAP.

I have been rather confused about the process.

After I sent the online application, do I need to send my passport and other documents by post somewhere? Or do I go to a designated centre for them to be scanned and do not need to send them away?

People on the inquiry phone said different things and I am confused. I don't want to send my passport away for 6 months.

https://visas-immigration.service.gov.u ... 1576788059

You need to follow the above link for this purpose where after completing the application form you will be directed to UKVCAS (UKVI's partner) to enroll your biometrics and scan your supporting documents which you can even choose to do by yourself means no original will be sent in post. Due to pandemic there is no super priority service but you would have to choose standard service which used to consume around 6 months before pandemic in few cases.
There are a lot of relaxation for NHS staff from visa rules to clapping so better to request your NHS employer that transfer of old ILR sticker into BRP might not be possible until the end of lock down.