I'm just asking this I watch a movie last night called 28 weeks later, part2 of the movie 28 Days Later. The movie takes place in London, England in the end of the movie you see a bunch of people who have the virus running out of a subway with that famous tower that is in Paris in the back ground. I know it's just a movie.

you the train from london St Pancras International Train Station new home of the Eurostar france and behond. lol if thats any help

It's called the channel tunnel and there are two ways of going through it.
Either eurostar trains that are for passengers and can be boarded from London and Ashford and Folkstone in England. This train is very fast.
The other way is to use a "chanel tunnel train" that can be boarded from folkstone chaneltunnel entrance. This train is for mainly cars and vans to ride upon. In other words, you can put your car on it.
The channel tunnel trains go from folkstone to calais and no further. The eurostar trains go from London to Paris or Brussels with some stops on the way.