Evisa during travel

Hi,
I now have my ILR and can generate code online, thanks to all who helped.

What will happen at the airport when I am trying to retun to UK. Do I generate a code before returning to Uk and hand it over to the airline check-in counter? How does it physically owrk when I am trying to board a plane retrun to UK?

some airlines confirmed that they needed to see you log in to your UKVI where your ILR is documented
(during check-in / final queuing for boarding)

Home office website previously said creating a code before travel and showing this to airline staff