I like this idea - simple and straightforward to make, but the payoff will be huge. It could be helpful to touch on nearby attractions, so tourists are better equipped to plan their trips.

Rather than just looking around, your video needs a mission: "Let's find the best market in London". Make this concept tighter and the video will be more cohesive.

This is a solid topic, but the default version is also very easy to blend into every other city food video. The question I'd push on is: what makes your version the one worth clicking? Right now the broad structure is "visit famous places, try food, compare prices, rank the best one." That works, but it is also the expected version. To raise the odds, I'd sharpen one distinctive angle before filming. For example: 1. Best street food under a fixed budget. 2. Most overrated versus actually worth it. 3. Tourist-famous versus local-favorite. 4. Best value, not just best taste. That gives your title and thumbnail a cleaner argument and makes the video easier to remember. I also think the strongest part of this concept is probably the comparison, not the travel montage. So I'd bias the structure toward clear judgments and quick scorekeeping. If you had to make the viewer choose in advance, what is the one comparison your video is settling for them?