We have run several Ard Boys tourneys in the past. This year GW has done a fine job of scheduling them on the same day (weekend) as Magic pre-releases... which is a terrible, terrible idea and makes it extremely difficult on us.
As far as flexibility goes, there is some... but it does no good. Last time around they told us we could run it on the Saturday or Sunday. The problem with that is the pre-release is an "all weekend" type of thing.
As it looks right now it seems unlikely that we will host the Fantasy Ard Boyz tournament simply due to scheduling conflicts. I would keep an eye and ear out for a Fantasy event sometime in the foreseeable future though.
Things may change however... I will be talking with GW on Monday.