The range of available launchers for a "small mission" is limited due to considerations of size, performance, and cost.
SOYOUZ is the most used rocket in the world. Its capacity in low orbit starts at 7,5 tons. It is 49 meters high and weights about 310 tons.
The CoRoT launcher is a Soyouz rocket version, built in Samara by the STARSEM company, which handles its marketing and exploitation.
The shareholders of STARSEM are Arianespace, EADS, The Russian Space and Aeronautics Agency, and the Samara Space Center.
The launching will take place in Baïkonour, Kazakhstan.