It is quite normal to feel uncertain, insecure or plain scared upon your acceptance to university. Most also feel other emotions, especially excitement and exhilaration.
Most people are somewhat apprehensive at first, but just hang in there.
Few people really know what a university is or does before they go, and even fewer know in advance what is expected of them. This leads to many new students, especially at first, feeling worried. The information contained here should help you to weather these early storms and hopefully will help to calm you down. Although studying is frustrating and tough it is also very rewarding and satisfying. It can be like climbing mountains - you have a lot of hard slog on the way, and sometimes when conditions are poor you wonder why you bother, but when you reach the peaks it can be very fulfilling.