The answer below is simply not true. I can't stress it enough. The responder is 100% wrong. You absolutely can have a wedding in a Catholic church after you've had a civil service. How do I know? Because my Catholic wedding is schedule for this November, nearly two years after my civil service. Wrong wrong wrong.
A Catholic is not allowed to undergo a civil ceremony. If you mean to do a civil ceremony and then follow it with a Catholic ceremony you will be refused a Catholic wedding. The Catholic Church only sponsors the sacramental marriage that It witnesses between its members - it is considered an implicit denial of the Faith to undergo a non-Catholic ceremony for whatever reason and thus it is sinful. If you originally had a civil ceremony and then later found out you are not married since you as a Catholic require a Catholic ceremony, you will usually be permitted after consulting with a priest who must first examine the marriage history of you and your partner to ensure there are no impediments.
In some countries of Europe, such as France and Monaco, the State denies the civil existence of any marriage which has not been duly authorized by an agent of the State. Therefore, to be legally wed in the eyes of the law, all couples living in these countries must have a civil ceremony performed first, and afterward, if they care to, a church one. In the eyes of the Church, however, a civilly married couple is not married until after the church wedding.