I have just purchased Serenity but have recently found out that Firefly should be watched before this film. As the show was axed after 14 episodes do i assume the film ties up the loose ends of the show?will the film confuse me if i haven't seen Firefly? Any help would be appreciated.Firefly - The Complete Series [DVD] 
The movie does tie up parts of the "loose ends" (so to speak). Joss Wheedon did a 3 part comic series (by Dark Horse comics) titled "Those Left Behind" that covers the missing ground between the series ending and the movie start. Written by Brett Matthews, Joss Wheedon is credited with the story.
The movie, whilst complete in itself, is left a little open ended, so further movies (or a revisit to the series) could be made. Watching the series is not essential, but would certainly help fill in some of the back story for the film