Hey 747girl,
I had a BA assessment this week. There were about 12 of us there and we were split into two groups. Firstly we had our height measured and we had to sit in a crew seat and adopt the brace position. Then we went off in our groups. We had to introduce ourselves to everyone and then do a group task. After the group task we all went back to the reception area. The first half of the group were then called individually for their 2:1 interview, whilst the rest of us had a presentation on BA. Then we swapped over.
If I were you I would really prepare for the 2:1 interview and have lots of examples ready.
We were all then told on the day whether we were successful or not (they said they didn't usually do this, so don't know whether this will happen with your assessment day).
Unfortunately I didn't make it
so I guess I will just have to try again in 12 months! (I think it was down to the fact that I didn't give some very good examples in my 2:1). There were no tests or exams and overall the day was very relaxed and there is nothing to worry about. Hope this helps and good luck!!!