Yup, it was a good day out, and even if you don't get through, you'll learn a lot from the day. It's a good idea to prepare thoroughly for the interview, as they will ask you a lot of seemingly innocent questions that are actually designed to root out your weeknesses (if you have any!). I know this all sounds obvious, but I have a feeling I probably tripped myself up by doing too much talking and not enough thinking.
If you've got FB coming up, then the best of luck to you. Let us know how you get on
Pie.