Maybe take this with a pinch of salt, as I did not convert my AC at Slaughters (though their reasoning was one of "way of thinking", not competency), but I found it really helpful just knowing that it's people on the other side of the table you are interacting with, not robots.
You are there because you are good enough; no question about it. This is just the final check for suitability.
Try to genuinely enjoy the conversation and get on with them. You are a much more memorable candidate if they can actually like you as well! Also, as long as you are comfortable with basic scenario responses, you will be able to adapt your responses to different questions - they tend to follow the same sort of themes just with different manners of approach.
Good luck though, you will smash it I'm sure.
