When I was back in school some people I knew created an hour long film based in Medieval England. The script they wrote was really good and they managed to get the actor from The Lord of the Rings - The Two Towers who stands on Helm's Deep and says "Fire!" (The one with only one eye) to play a part in it. Not a biggy, but none-the-less it's something.
The film featured swords, nudity (she was over 18

) and horse-back riding. It was good fun, but it was also VERY well planned. The guys wanted to go into films and they thought this would be their best chance.
Their site is at
http://threearrows.co.uk/ , from what I hear their premiere hitched but things still went fine. The two main people involved sent off the DVD to several angencies and have several positive leads.
So it goes to show, you're never too young to start thinking big.
Now I know you don't plan to do this for a career, but hell, it's a lot better when everything has been planned before hand.
EDIT:
Check out their gallery -- Try and spot Jesus masquerading as a camera man!