Hello!
Huge congratulations on receiving an AC invite! It's totally normal to not feel prepared - I only had a couple days to prepare for my
Reed Smith AC as I completed it the week following a vacation scheme, so I'm sure you've done more prep than I did!
I have quoted a post below on some previous general advice I have given for the types of tasks that might come up during the AC (although they may have changed the process!) - hopefully it is a helpful starting point! My main tip would be to make sure that you have a good understanding of the sectors that the firm works in, and how recent events and news stories could affect the firm's clients in those areas. I'd also prepare your answers for the most common interview questions (e.g. 'Why Law', 'Why X Firm', 'Why You', etc.), as it is always useful to know these in case you get asked. Lastly, have confidence in yourself and your abilities - the firm clearly sees that you have the potential, now it's about showing your interest and fit!
Best of luck - I'm sure you'll do great!! 💪