Travel from cdg to AMS

There are direct TGV trains from the airport to Brussels-Zuid Station. From Zuid you can catch the regular Inter-city trains to Amsterdam Centraal Station. For the best price you should book your TGV ticket in advance at www.tgv-europe.com (when the site asks you where you live say "UK"). From Brussels to Amsterdam no advance purchase is required... you can purchase your ticket at the station, fare is about 35 euros.

Two things to at least look into:

1) Since you are already at the airport, fly, on another carrier

2) Change your ticket to AMS