Basically, you choose what you want and go to one of the machines and then walk up to the special queue and just get your drinks. No queues. It is really quick.
One time I had a short delay as there was just a regular punter arguing with the barman who wanted to buy drinks with cash and didn't want to queue with everyone else. But the barman wasn't having any of it. Good for him. Downside is that you end up with a lot of glasses to return at the end of the night