Bearcat,
It's ok. My posts dont appear straight away for some strange reason.
Just to let you know, I spoke to FTE and he confirmed that it is a one day process.
All of the tests, including written tests, aptitude tests, one to one interview (which was not mentioned in the email) and the group exercise. If you are successful on this assessment day then there is the final interview with British Airways at Cranebank.
Hope this helps!