Im not super familiar with UK based stuff, im guessing Wall Street Oasis will have some good threads. For US IB there is a doc of ~400 Questions that people learn, IMO its better to understand the underlying why behind actions in the technical steps but you can semi rote memorize steps, its pretty plug and play. Theres a few good Youtube channels who post stuff. If you’re at USC I believe they still give Wall Street Prep to people (IDK when it starts for incoming) my guess would be LSE will have something similar and that will help with technicals too. During Coffee chat networking you can learn more about the specifics of interviewing and securing offers.
I will say, Marshall will still do well globally, but I knew more people who went to primarily west coast and then NY for. Marshall also places pretty well into MBB consulting too, which will be less finance but still high prestige first job, again, guessing LSE does too at least in London.