I agree with those before me. I'm like you- I get frightened pretty easily by stuff. It's kinda funny, because I'm pretty cool with things in real life, but onscreen? Nope. Still, Silence in the Library and Forest of the Dead are two of my favorite episodes. Doctor character development? Check. Interesting, new monster? Check. Interesting concept? Check. Giant, planet-sized library? Check! Still some funny moments? Check.
Watch it, you won't regret it. It's creepy, but in a good way.