Just a quick heads up....
I was just asked by SomeGuy about whether there was a lower poly mesh to use than the one supplied for the challenge as he felt it was too high. The answer is basically no there isnt.
The mesh is there for you to get going so please edit it as you see fit, delete what you want. Building a head from scratch takes long enough as it is, as does creating a fairly good UV set.
So feel free to do what you will to the mesh in order to make it work for you.