travelling on the eurostar or that train that goes to france?

i was hoping to go to france or somewhere in europe for the day and of course going for the day im going to travel by the train.
i know theres the euro-star and im sure theres another train that travels to france and from there you drive to belgium etc. as its just going under like through a tunnel.
ill get to the point,
my question is
How old do you have to be to travel by train to france
thanks x

Eurostar is the passenger train that goes from London St. Pancras station to Paris, Brussels and Lille. It only carries people (and their luggage), not cars.

http://en.wikipedia.org/wiki/Eurostar

The train that carries vehicles, and which you can drive your car onto, is called “Eurotunnel Shuttle”. It goes between Folkestone in England and Calais in France, and it was previously known as “Le Shuttle”. Foot passengers (without vehicles) cannot use this train.

http://en.wikipedia.org/wiki/Eurotunnel_Shuttle

Both the Shuttle and the Eurostar trains go through the Channel Tunnel between England and France.

You must be aged 12 or over to travel alone to France on the Eurostar, and if you’re aged between 12 and 15 you must have a written letter of consent or signed consent form from your parent or guardian if you’re travelling by yourself. Children aged 11 and under can’t travel alone on the Eurostar and must be accompanied by a person aged 16 or over. They would almost certainly need a consent form too, signed by parent or guardian, if the person accompanying them is not the parent or guardian of the child.

I don’t know of any age limits for the Shuttle, but under UK law you’d have to be at least 17 to drive a vehicle on board anyway.