John Lewis Partnership IT Graduate Assessment

Hello there. I have been invited to an assessment day of John Lewis IT Graduate Training Scheme. All I was told was that there would be a presentation on the scheme, a short interview and an aptitude test. Has anyone attended this first assessment before? Just wondering what to expect, what sort of questions, aptitude test, e.t.c. I called the recruitment line but they seemed sort of discreet about letting much info on the assessment. Was only told there would be a diagrammatic test. Any help or tips would be appreciated, as Ive only got a week. Thanks.