Do I need a visa to take Eurostar from London to Paris?

No matter what means of transportation you take, you need to distinguish between Schengen countries and European countries. Britain is not a Schengen country, but France is, so you need a visa to travel between countries.

For example, if you are an international student and want to travel to Paris, you can get a short-term tourist visa from the local French consulate, and you can legally stay for at least seven days. If the destination is not Paris, you need to submit a destination visa and proof of the hotel you booked, as well as photos and visa fees when applying for a visa. Basically, visas need to be queued early in the morning, and it is best to pack the information in a folder (impression points). Immigration officials usually ask some questions, as long as they answer truthfully. If it goes well, you can get a visa this afternoon. And this can be handled by someone, as long as there is a reasonable reason.