This information is 3 years old. Quite a comprehensive assessment:
1) ATPL theory test, various questions on law, met, PofF etc - just go through your ATPL notes briefly
2) Personality test
3) Interview - who are you, what do you want, what would you do...
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and if you get through that..
4) Simulator assessment, the assessor who did mine is now gone so no point posting what he got me to do because it was all personal choice of the assessor.
Like I said - 3 years ago so might be out of date