Dear Tom,
I've just read your letter. Sorry I haven't written for ages, but I had some problems with my parents too . Now I'm free to write and I'll do whatever I can to help you with solving the problem with your parents.
I think that you should be more confident. You shouldn't let them tell you what to do because it's your life and you have the right to do whatever you want. I mean, you are already 19.
Actually, I agree with your parents for one thing. You would better save your money for university not for the vacation. But considering the fact that you'll probably go there next year you can always tell them that you have enough time to save more. I'm sure that they will understand you.
Nevertheless, in my opinion, if you want to study you can study everywhere. For example, you can tell your parents that it`s not necessary to study at home when you can do it outside. You don't have to be isolated, right?
About the danger of you and your friends going alone I`d say that it`s completely normal and like I said you should be more confident and brave to tell your parents that you are not a little kid anymore. I`m sure you can cope with the problems at the vacation and there won't be any difficulties for you to do it. The only thing to do is to show them that they can trust you.
So I hope I helped you. Write to me soon to tell me how it went.
Your loving friend ,  Matei .