How do I travel from London to France via train?

This weekend (12th April-13th April) I need to get from London to Berck Sur Mer in France (roughly about a 2 hour drive west along the coast from Calais) for the kite festival.
I will be travelling on my own and the travel websites aren't being very helpful as they are either for train journeys within the UK or just within France. Please help someone!

Go to a travel agent in the UK.
They should be able to work out everything for you, as well as supply the tickets you need. It's what they do.

Have a look at this website:- http://www.seat61.com/
It's very helpful about rail travel throughout Europe.

Berck-sur-Mer doesn't seem to be served by railway, but nearby villages as Verton and Le Touquet/Etaples does. You'll need to use the Eurostar from London to France then do a minimum of two changes with local trains and/or buses.

My favotire trick to search in european timetables is the swiss federal railway's website available at:

http://www.sbb.ch/en/index.htm

or the french verision if you prefer:

http://www.cff.ch