Visiting Europe for a month, any recommendations?

Flying out in a couple days, we already have our locations booked, and some activities planned, but largely we just plan on just chilling / figuring out what to do once there. Here’s where we are staying / how long

Italy (Rome / Florence) - 4 days
Switzerland (Interlaken / Lucerne) - 4
Munich - 4
Vienna - 4
Prague - 3
London - 9

Anybody been to these places? Florence and Interlaken are our most planned already, but if you guys have any ideas of cool things to do, places to visit, food to eat, especially for London, where we’ll be a long time, let me know. Never been to Europe so I don’t have too much of an idea what to expect.