I would ask, since you have to move room anyway, if there is another hotel that you could stay at as you don't want to stay in a smoking room. Alternatively, try phoning the hotel yourself and ask about the likelyhood of there being a room becoming available by the end of the week.
I have to say though, are you convinced that this is the right job for you if you are willing to give up at the first hurdle?
I quite agree, I would not like to stay in a smoking room either, but if I made it plain to the company that I was doing it as a one off, I think that if I wanted the job enough, I would be willing to take the chance that I might get to swap the room before the week was up directly with the hotel.