Dear 16 Year Old Jess,
Firstly, happy birthday! The first thing I would tell you is to enjoy the day you're about to have, and cherish the people who have made the effort. Your night will end in the worst way possible, and you'll be crying and wondering why you've had to end it with your boyfriend who just did not care. He is not worth it! And one day he will want you again and by that time you will have moved on. Don't waste your time on him, because in 3 months time you will meet the lovliest, most perfect guy in the world. And this time, it will actually be real love. And you'll be with him forever. :)
Try not to be an adult. You're not. You're still a child and you've got so much to learn. The one thing you'll learn pretty soon is that people will come and go, but ultimately you need to be independent and learn to be strong on the inside. Don't underestimate that inner strength you know you have.
As silly as it may sound, enjoy school a bit more. You won't miss it when you leave, but you will wish you didn't want it to end so quickly. And don't worry about trying to make other people happy, it's your life, and if people don't agree with your deciscion of not going to uni then (beep) them. Plus, you're going to join the Open Uni in 3 years time anyway!
Stop worrying about the future, it will all work out, in a much better way than you imagined. Enjoy every moment and don't look back.
Lots of love. :)
PS Save some money!