The Aldi Area Manager graduate scheme is heavily oversubscribed mainly due to the above average salary on offer plus promise of swift progression. The main area of questioning focuses on leadership experience either professionally or socially as many candidates are recent graduates without a great deal of work experience. Captain of sports teams, academic groups, Scouts etc are popular choices if you don't have a great deal of work experience.
My advice is be yourself as if you try to be something you're not and get the job you will not enjoy it and no matter how much the salary is, it's not enough, you have to enjoy the challenges you will face in order to do well.