Assessment Centre

I have been invited to an assessment centre in hobbycraft in a weeks time for about 3 hours and the brief I was given said that the agenda may include 'an overview of the store, a team excercise, 1 on 1 interview and a shop floor walk'.
This is actually my first time applying for a job so i'm nervous about wether this will include verbal presentations or any in-tray excercises. I wanted to know if anybody could explain these activities any clearer to me and what to expect from the overall experience?