Hi Bunjies, congratulations! We had tickets for a recording in the summer. It was good fun. The drill is as follows (this is basically what's printed on your ticket but just to clarify that they really mean a lot of this):
Your e-ticket says that doors will open from x time and recording will start at y time.
*You need to know that if you turn up at x time you might be too late.* They have so many no shows that they issue a lot more e-tickets than they can accommodate in the radio theatre to make sure they're full. So you need to be there a bit before x time, with printed copies of your tickets - that's essential! The ticketing operation is v. efficient - you and your partner/friend will both have to be there and they will put a sticker with a number on it onto each printed ticket.
From the time they say you can go in (ie x time) you can queue up to go through the airport-style security to get into the bar area. The bar usually serves food as well as drink, it's quite cheap and there's plenty of seating. You can look down into the newsroom while you wait.
Eventually they will start calling people through to the radio theatre. They start with people invited by the production team and then they might call everybody with a ticket numbered 1-50, then 51-100 and so on till they get to about 300 which is the capacity.
It took a while to get everybody seated and then there was a bit of a warm up when Sandi Toksvig introduced the panel. The actual recording might have taken a couple of hours, tops. I think you could assume that you'll be out of there by 9.30 at the latest if the recording is due to start at 7.15/7.30.