Perhaps you should bump
this thread also and let everyone know where you're going. It's not the same, but there is a little bit of overlap.
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Oh man, I'm going to try and give you a little bit of my perspective and my experience from going to college. I graduated about a year ago with an engineering degree here in America. Since you're going to the UK for college, YMMV, but hopefully, some of the engineering things will translate over to across the pond.
Everything others have said are true.
Be prepared to work hard if you want to do engineering successfully and meaningfully. This is not meant to scare you at all, but if you are serious about going into engineering and doing better than just skating along, work hard (and smart). Throughout my college career, I've found the adage that you should expect 3 hours of homework and studying per hour of class time to be true. On top of what others have said already, there will be lots of homework and problem sets, many of which will leave you wanting to tear your hair out. You WILL experience homework and problems where you sit there staring at it for an hour and you still don't know how to begin, or being two hours into a problem before getting the answer wrong. As discouraging and frustrating as that will be, especially when it's 1 am and your non-engineering friends will just be about stumbling back from the pub drunk, don't let it stop you. Try to start and do the homework early, and take advantage of professor's office hours. As others have said, you get as much out of college as you put into it.
With that said, participate in extracurricular activities that interests you. I don't know whether and what extracurriculars you participated in in high school, but when in college, pick one or two, and be really involved in it. Start as soon as you can. Since you are going into automotive engineering, join the
Formula Student team at your school. It is an amazing experience and a fantastic opportunity to learn and apply engineering to a real problem, learn project management, and the teamwork and the "soft" sciences and business side of being an engineer. That program will teach you so much about how automotive engineering actually works. Oh yeah, you ever want to go work in F1? Do Formula Student. Remember, often times in engineering classes, you are limited to the theory on the board and in homework assignments, with a limited application through labs and a senior capstone project. Don't rest on your laurels, go and actually apply it in real, complex problems. That's going to give you a significant advantage over others when you go and apply for jobs.
With that said, time management will be a huge part. You're in college because you want to be there. Beyond a few very introductory classes, there's no hand-holding. You sink or you swim. If you don't go to class, no one is going to say anything, and I'll admit to having my share of class-skipping. But be careful and don't make it into a habit, you can fall behind very very quickly, and it doesn't endear you well to the professors. Go to class unless you absolutely need to skip it.
Another part to time management is that you'll be responsible for figuring out when to cook and eat, when you'll be doing homework, when you'll be going to class, when you'll be doing chores (laundry/basic dorm clean up/etc.), when you'll be socializing and when you will be sleeping. You're going to have to figure out what's most important to you at any given time, and prioritize and figure out something that works for you.
For freshman year, before you are 100% focused on your degree of choice, go figure out how many "extraneous" classes you can take, and take the classes that purely interest you. There are so many classes and interesting subjects that you may find something else that you want to major or minor in. At my university, I've seen classes as general as "20th Century world history" to classes as specific as "Exploring sub-Saharan African women diaspora through literature", or from engineering statics to mechanical vibrations. Try to find out who the good professors are, and if you can, take classes with them. Don't lose sight of your goal, but it's ok to take a detour here and there to learn and gain additional experiences in other subjects.
I wrote a fairly long post about a year ago on going into engineering and what it really entails, if you are interested, I can dig that up for you.
Best of luck in college over in the UK. Everyone freshmen there will be new, and it's the time now to make those bonds. Work hard, don't drink too much, be open and make plenty of new friends and connections and have fun.
Oh also, for the love of God, while you're in the UK, please drop the "I'm not American, I'm British!" bit. Being American is going to get you laid a lot more often.