I'm speaking from heartfelt experience here, as I myself have been through this labor-intensive process, and I have reaped the rewards. This Autumn I will be attending Yale University: THIS COULD BE YOU!
This would be a big commitment: not just because you'd be planning to leave your home country and start a new life on your own, but also because of the sheer hard work and effort required! Is this what you want? Find out the differences between UK and US Uni: How long do the courses last? What's the 'Liberal Arts System'? What classes as a Uni, and what classes as a College? These are all things you need to discover.
Handy Hint: Are you the medical type? Or perhaps the courtroom is irresistible to you? If you're after a career in Medicine or Law, you may be best off in England-courses are shorter, cheaper and focused to UK professions...Seriously, if you want to be a doctor or lawyer, stay in the UK!
Get your school/sixth form on your side and let them know how interested in studying abroad you are. You'll need references, sign offs and a counsellor so make sure they know who you are! Also, get your parents on board! Make sure they've heard about your plan before you announce your immediate departure in September! They'll be vital to applying for financial aid if you can't afford the fees, so get them in the loop!
You may want to consider some real help...it's a massive process and you may need support. You can contact Universities in the US to put you in contact with a current student at their College who was originally applying from overseas, they might have some insight. What I would really recommend is looking into the Sutton Trust and Fulbright Commission. The ST is for low income students for Undergraduate application (you haven't already got a degree) and the Fulbright Commission supports Postgrad students. The ST are super-I've met the founder of the charity and worked with all of its amazing staff and they are absolutely fantastic! I know MANY students they've helped get funding to study in the US, not just me! Their work is second to none....give them a google!
If not, don't fret. The US college system has some amazing Scholarship and Financial Aid opportunities! You can't take a UK Student Loan, and DO NOT consider commercial loans, but its still possible to go! The key is, where to apply. State Universities, like UCLA and the like, often don't fund overseas students so you'll want to target Private Universities (The Ivy League and so on) if you want aid.
The Crux of the Matter: If the Uni can afford to fund you, it's standards in terms of grades will be high. If the standards for a Uni's grades are low, chances are, it won't be able to fund you. Catch 22, I guess: Rich Universities have high standards.
So basically there are two types of US College: Need Blind and Need Aware. Need Blind Uni's just decide whether they want you or not, irrelevant of your ability to pay. We're talking Harvard, Yale and Dartmouth here, the top notch, super selective types. The Need Aware Colleges take into account your ability to pay as a factor in your admission: In other words, if a need blind place likes you, you're in-whether you're Prince William or Poor as Dirt. Need Aware places decide whether they like you, then let you in if you're Prince William, but might reject you if you can't pay.
I recommend the earliest Test Date you can manage.
This is the Standardized College Readiness test. You may have heard of the SAT but the ACT has a couple of advantages for British Students. Number One: It's more similar to our education. Number Two: They're both multiple choice, but on the ACT you don't lose marks for wrong answers-you do on the SAT. The ACT is scored out of 36, and there are 5 sections (Tip: Take the test with writing. It barely affects your grade, and sometimes waives the requirement of SAT Subject tests!) You definitely want higher than 30 in the ACT, and ideally over 32, because competition for Scholarships is going to be fierce.
You'll also want to take two SAT Subject tests, in your best subjects if you plan to apply Ivy League. Best bet is to do one in the Arts and Humanities (Literature is a good bet, or a Language test) and a STEM one (Bio, Pysics, Chem or Math I or II)
You'll write LOTS of essays. One is used for all Applications, and then each uni requires additional essays. Make sure they sound like they're in your voice, and give information about you!
Sit with your parents and fill out aid forms. You'll need to check the websites for specific information, but as a guideline, you'll probably fill out a CSS Profile, an ISFAA and possibly a COF. Google them. Start collating information now! Get last years forms and fill them out. The forms will change but often the information is pretty similar.
Send your grades from ACT. Send your Financial Documents. Send your CSS Profile if required, and fill out the Common Application. You'll need two teacher references, a counsellor to sign off and write a reference and your essays. GOOD LUCK.