Do you need to have seen the series to watch the film ?
Personally, i would watch the series first. It's only 12 episodes long and they're (in my opinion) way more entertaining than the film (and the film is one of my favourites. Ive seen it, literally, 60 times or more).
After watching the series, you'll know where each character came from, their history, why they make the decisions they do, or why a couple of the crew members aren't on the ship in the film... stuff like that. It's worth it.