Sure your work load will probably be heavier than what you're used to, but you'll also probably have more time to take care of the work. The key to handling the workload is organization and prioritization. You will quickly learn which types of assignments deserve the most attention and which types can be put off. If you use your time wisely, you shouldn't have too much of a problem keeping up. If you do run into problems, use the support system built into just about any college.
Some students worry about which courses to take and which major to choose.
Most students know which major they want to pursue by the time they have to formally choose one. Even if you are unsure or later decides that your choice wasn't the best one, there is usually time to switch majors. Don't forget, your major doesn't have to determine what you do for the rest of your life. Often the key to doing well academically in college is to choose a major in a subject that you enjoy. Most college fears are best confronted head on.