Erm, yeah, the audition process is bloody weird. You go to your local Beeb location, and they take you in one by one and ask you a rake of general knowledge questions. Worst thing is, they don't tell you if you get them right or wrong, how many you got or anything like that.
Then, you banter with them to prove you're not some kind of crazed shut in, and they send you on your way. They tell you to wait about for two weeks, but they'll get back to you in a coupla days if you're in.
As far as the screendate, I don't know. my round is filming on the 31st of march, and it's the second batch being filmed, so it'll be about half-way through the series, so some time in april, I guess, maybe into may, but not too much, as they're filming the semi-finals then.