You can travel from Paris to London in less than three hours with the Eurostar, a wonderful opportunity for spending a couple of days in London with shopping and musicals. Or if you're already in London, then come and experience the City of Lights. London and Paris are practically neighbours now.
The price for adults starts at 77€ for a round-trip, and if you're lucky to be under 26 years old, you can get the tickets even cheaper, from 60€. Eurostar offers packages with train, hotel and car included. There are often campaigns and discounts for the travellers, so if you want to go, you better keep an eye on the site and see what's available for you. More information can be found at: http://www.eurostar.com/
The ride is fast and it's much easier than taking the plane. Check-in at Gare du Nord in Paris is about half an hour, which includes passport control. So don't forget your passport. You'll arrive in the middle of London, ready to explore the city. The train is fast, especially compared to the old IC3 trains in Denmark. It's a comfortable and relaxing journey.
The train departs from Gare du Nord in Paris proper, which is easily accessible with metro and RER. Gare du Nord is a hub and several TGV lines depart from here. In London the train now arrives at St. Pancras International which is next to Kings Cross and located in the northern part of central London.