Originally Posted by
Microwave
I'm not sure what the gate agents would say if you turned up without having checked in, but in theory they should be able to handle formalities for you as long as you've not left it too close to departure time. Personally I would only skip the barkers and "The Room" if I had my BP in hand and just wanted to avoid the scrum for the security sticker, or if somehow I'd completed OLCI but didn't have a BP and just needed it reprinted (which the lounge could also do).
I'm more envisioning the case like our flight in January out of Bucharest. We were checked-in, all the way through, but the agent at OTP was unable to give us BPs beyond the OTP-LHR flight. If the line were not bad, I'd probably still brave The Room, but I'd have little reservation about bypassing if it looked bad.
Then look at the after-desk. Failing that, BP at the AC and questions-and-answer at the gate.
Cheers.