I like a lot of people have said here just look at the positives in life. The more time you think about negative it will slowly bring you down. Like you said yourself you are working on your shape and keeping at it which an awesome job! You know that working hard gets achievements so congrates on that. The more you think about turning that milestone the more you will worry, just let it happen and keep on with what you were doing before. With regards to people in general some of them are closed minded like you said but their are other that aren't people just like you, you just have to find them. Starting a course is always a good start meeting people and decided who you like and who you don't.
So try to be open minded with people we all have our flaws but its the good you look into people. Good luck on turning 18 and as you said if you want to become successful you will be driven to meet you expectations!
I think most of your "frame of mind" is right, but some of it isn't. It's really good that you're going to start TAFE and that you are pretty much just trying to be a good person. but I don't think you should have this permanent mind-set that everyone is ignorant and fuck everyone I'll just be alone cause it's better/easier. Everyone needs someone to talk to and have a laugh with, sometimes
Not all people are close-minded and ignorant.. I hope you can open up yourself to those people. I've figured it's okay to be alone, but finding friends who we can trust is a big weight lifted from us..hope that helps..