SNCF's timetable is available on their UK website:
http://www.sncf.co.uk/
However, Die Bahn's website is generally more user-friendly:
http://reiseauskunft.bahn.de/bin/query.exe/en
(Die Bahn has the times of all trains in Europe. You can use the site to plan journeys within a single country, or across many borders, with ease).
Disneyland Paris is served by Marne-la-Vall�e rail station.
You can also reach it by taking an eastbound RER train from central Paris, on line A. (Make sure that the destination is shown as Marne-la-Vall�e, and not Boissy-St-L�ger, as the line divides after Vincennes).
Security at French rail stations is probably as good, or as bad, as at UK rail stations.
Chris