I've just rung a Disney media contact of mine and they have confirmed that the event is indeed sold out. It apparently sold the last of its tickets just over a week ago.
I asked about the lack of advertising in this country and was told that is is really because of it being one night in a different country that it wasn't worth spending the budget on and it was more aimed towards to the Spain/France/Belgium market.
They did also say that there is a chance that many people won't be able to go due to the French strikes so there is a slim possibility that tickets might become available on the day but she did want me to emphasise that you shouldn't be making a special tip to the resort just for this event as there are no guarantees.
If you can't make it, I will be covering it for the Disneybrit Podcast, which is a UK based Disney show and I hope to have some video footage too. If you want to be kept up to date with all the Disneyland Paris stuff then check us out (Disneybrit.com or Disneybrit Podcast on iTunes). We announced the Terrorific Night back in September.
Adam