Slightly late response, but I've done this too. It was just my friend and I on the tour, but we booked in advance, as they don't run tours everyday, and if you're the first person to book, you specify the language of the tour. I.e. if you decided you wanted a tour on a Friday, but they'd already booked someone French in, the tour that Friday would be in French.
We really enjoyed it, found out lots of information and saw little quirks that we wouldn't have noticed otherwise probably. We did get taken 'backstage' to see Star Tours in action, unfortunately Star Tours was down at the particular moment in time, but it was still fun to see it from behind the scenes.