Don't assume that only one program is offered. Many large martial arts schools also run self-defense clinics. Take time to do a little 'leg work' before deciding which classes are best for you. If you do decide that you want to attend a school on a long-term basis, be sure that the style and philosophy are waht you are looking for. Some schools put a lot of emphasis on sparring and tournament preparation while others strictly teach street-style defense.
Some styles also require students to train in the use of one or more traditional weapons.
This may also influence your decision. The martial arts provide a wide variety of disciplines for the improvement of many aspects of your life. With a little preparation you can make the most of your experience, and perhaps you may find an endeavor that lasts a lifetime. Martial arts schools provide relaxation, agility, and an appreciation for other cultures. Before you decide on baseball, football or hockey, read this article.