HypersomniacLive: Depending on the laws of your country, you may not even be eligible for leave time with a 3mths contract.

As adaliabooks said, a contract can't take away statutory rights, but what those rights are in your country depend on your laws. My advice is to consult with whatever public office has authority over employment matters. Because, unless someone here knows your laws inside out, you can't rely on the info anyone gives you in this thread.