5 Hour Process in 4 Stages
GCSE Mental math test - Really simple math (Addition, Subtraction, Division, Squares, Pythagorus)
Ven diagrams test - They send you a link for help on this and although they say it means nothing it basically tests whether you're apt enough to understand basic sets and unions for databases and SQL (according to the techie's present on my day).
Aptitude test - This is a combination of all skills - they test your verbal & non-verbal reasoning, situational analysis and office room conduct - You can find plenty of these online to do if you're worried.
3 Quick-fire interviews - One about your degree, One about why you want to work with FDM, One about "who you are"