Alton Towers have just posted a new video about the ride.
If my ears do not deceive me, that main instrument we hear is a hurdy gurdy. As a huge fan of folk/celtic music and the various instruments used in the genre (the weirder the better), it's one of my fave instruments. Screw all this "world's first coaster to fuse wood and fire", should've gone for "world's first coaster to use a hurdy gurdy in the soundtrack"! That would've got my attention way more for sure
This section of the article
from Merlin that I have linked, tells us a bit more information. They also slightly touch on some pre-show information without giving a lot away. On top of this, the article basically confirms that special effects will be used on the Wickerman structure, and not actually fire effects which is kind of a downer. I would suggest you read the article, it gives a lot of the story of making the artwork and gives information on the ride.
Quick edit: It seems that this theming structure is called the "Wicker Beast" according to the article. I really like the sound of that name, and happy to see it actually has a name, like Smiler's "The Marmiliser"
Looking at how it's worded, I'm pretty sure they're only describing it as a "wicker beast", not naming it. The article refers to it in a number of ways, "wicker effigy", "flaming structure"... If it was capitalised there might be something in it, but since it isn't, I highly doubt it's the name. In fact I highly doubt it'll even have a separate name. Everywhere else (including official media) is just referring to it as the "Wicker Man", and the GP are unlikely to latch on to an alternative name, everyone's just gonna end up calling it the Wicker Man.
The bit about "special effects" is more interesting though. Does indeed make it sound like there won't be real flames. But that would make the whole "world's first" aspect even MORE pathetic considering there ARE wooden coasters out there with REAL fire effects.