Originally Posted by corporate-wage-slave

At T5 you can do this almost anywhere (not sure if the new BA staff tablets do them?) but if using FT North just go to the Customer Assistance desk to the left, and FT South there is a visa check desk just in front of the gates. At the moment the T5 gates won't let you through and will say "See BA staff" if you haven't sorted this out beforehand, but until this message appeared you didn't know before trying.

It's a bigger nuisance at other stations, if you haven't been to the lounge or the lounge is Third Party, since it then bleeps at the gate on boarding, and it can take a bit of typing by the gate agent to resolve. It doesn't take long, but you can feel the eyes of whoever is behind you in the queue, hence its usefulness.

And yes at T5 it is part of Ready To Fly - the software indeed is all embracing and if you get past the gate, you are indeed "ready to fly" - all checks have been completed - time, visa, flight still running and so on.