Moving away from home for the first time and into university is a huge transition and people adjust differently. Many universities have a personal tutor/student mentors especially for freshers, maybe you can book a time to talk through with them. There are probably a lot of other people going through the same situation, so please don't feel alone! I don't think you should be thinking of withdrawing at this stage. The most important thing at the moment is getting enough rest, so that you don't continue missing lectures, otherwise you'll start falling behind, which may be the reason you're not enjoying your course.
Hopefully, you'll be able to adjust and find a focus. If you're a little apprehensive towards making the first move/ saying "hi" in a large group, why not start off by joining a society that is relevant to your course. That way, you may be able to understand and enjoy you course a little more, as well as make some friends this way.