Interview at the assessment centre? Due to cost and sim availability, I'd be extremely surprised if they put you in the sim prior to interview. They want to know if you'll fit in to the "Orange order" prior to any technical/non-technical assessment.
Just read.
This will consist of an assessment centre and, if successful, a simulator check.
First assessment centre THEN if successful the SIM ride.
Assessment centre will most probably consist of Group exercises, english test, system test on the Airbus (for those type rated), and finally one on one interview.
For the record, i am type rated and I got the two e-mails. So not sure about the TR and non-TR e-mails.