Just because you get married, that does not mean you have to have children. However, it is something you better agree about with your spouse, or there will be trouble, as there is no way to compromise on that: You either have a child or you don't, there is no halfway.
If you are sure you never want children, you should get yourself fixed. A vasectomy is safe, effective, convenient, and over a lifetime, inexpensive for birth control. Of course, if you are lucky, you are naturally sterile, and won't need it. I believe it is customary to test for sterility before they will perform a vasectomy, as they don't want to do unnecessary surgery, even if it is just band-aid surgery like a vasectomy.
Naturally, if you went out whoring afterwards, you would still need to use a condom, for its prophylactic value. But with a steady partner, when both you and she have been tested and found to be disease free, you don't need to do anything and can just have a good time, without worrying about an unwanted pregnancy and how you might otherwise end up paying child support for the next 18 years.