After passing the online tests you get invited to do a phone interview. This was quick, took between 30-45 minutes. The interviewer was super nice and tried to make sure it was an easy and comfortable process. A few hours after the interview I was invited to an assessment center. Prior to the date you gets sent an information package with regard to what you can expect + how the AC would be structured. My AC interview was with a partner, which seems intimidating however the interview itself felt very conversational + laid back. Most of the partner interview questions in the AC were the same as the phone interview ones, I'd say you should be prepared to talk about topical issues within the field for both interviews.