I would look at the interview section/guide on here for TS. Their process hasn’t changed for a while, so in addition to the more recent comments...
One of the more relaxed interviews, as far as interviews can be. The Partners make a real effort to put you at ease and have a conversation. Know your CV well, be able to back up choice, and be prepared to answer the typical why Law, why TS.
Be prepared to get into a mini debate and be pushed on your point of view. So have an opinion and don’t sit on the fence. There aren’t any right or wrong answers. It’s more about how you can think about issues, consider new points/variables.