You won't be alone. One in four people experience mental health problems at some point in their lives, and at a stressful place such as Uni there will be many others with anxieties, phobias, depression etc. Your Uni should have a support service of trained professionals whose job it is to help people cope and ensure that they get a fair chance. Speak to them before you go and also contact your department to explain the situation so that they have a chance to make any necessary adjustments. Since you are posting anonymously, can you explain which sounds are the worst? Most lecturers do the job because they like working with people and want to share their knowledge (not for the money!). They will want to help you (and are required in law to make reasonable adjustments for you)
As for looking young, again, don't worry. In the first few weeks you'll meet a wide range of people from different backgrounds. Some you will want to avoid, some you will think are a little odd but most will be feeling just as nervous and isolated as you to start with and glad of someone to talk to. The first few weeks can be a challenge in terms of gaining independence and experiencing a different way of life, but the rewards are massive.