Being scared about performing well on your first job is, imho, the best indicator that you will become one awesome person, sought by many companies. It means that you truly care about your work, which is by no means a given.

However, relax! You're only just about to start your studies. Until graduation, there's a lot of time to learn, make experiences and gain the necessary confidence. At the moment, the business world might seem like a far away place with strong characters and high demand for skill and perfection. You'll have to be a professional, who knows what you do. We've all been there. But believe me, all of my colleagues are just people. We are human. A company recruiting you from University will know that you have practically no professional experience. That's why companies usually have on-boarding programs, which give you simple tasks you already know how to solve, they will check up on you, make sure you understand everything, help you and then they will start to grow you into a colleague and an employee who one day will earn them money - but in the beginning, they will invest into you. Don't fret the small things. Hey, I fried a $3000 microchip plus its engineering sample controller board in my third week, because I created a short-circuit in one of the adapters I had to make. I'm still alive and employed at the very company I started out at!

I highly recommend trying out things you learn at University. That will give you a head-start, and you will be able to gain confidence in your skills. Making decisions and standing up to your opinion on how to do stuff is something you can learn! In your family, ask around who is interested in a cheap website. Depending on where you live, you might have to charge more or less, however for me, living in Western Europe (Germany), I charged 30€/h. It often took me many hours to deliver a crappy site, but you will learn that personal contacts usually are willing to pay more for a bad product, because professionals will easily charge ten times the money for the resulting homepage anyway. It's good for them and good for you. It will give you practical experience as well as train you start, plan and finish projects and get stuff done. That's the very thing you will be trained in later on in a company, and by having this experience early, you will have a smooth career start!

Also, stay online. By writing questions and answers, you can verify your knowledge or get a free correction. You can learn new things. The Hashnode community is a very warm place for people who want to improve themselves. I never had a mentor, but in the years on Hashnode, I learned everything I needed a mentor for (and still keep on learning). Now, I am a kind of mentor for my colleagues. Funny world, huh.

Everyone makes mistakes and most people are nervous for big changes like starting a job. That's okay. Reasonable companies don't expect recent graduates to know everything or be as productive as seniors.

It's great that you are learning new things. That's most of what you can do to succeed: study well, be curious and interested, and maybe some soft skills.

If you're doing that, try to not lose any sleep over it. You're doing well, perhaps better than many others. You'll enjoy it much more, and thus keep motivated, if you're not doing it out of fear.

P.s.: don't miss out on depth by frantically looking into every technology. You don't need to know every technology. Get somewhat competent at whatever you like before trying more.