It was really really fun to talk to bright young folks about exoplanet science and astrobiology. I've collected a few helpful resources below.
I mentioned the fact that I think coding should be part of the required curriculum in schools. Along with taking that new high school programming course when you get to it, you can get a head start now by teaching yourself.
The website Codeacademy has courses which are pretty easy to navigate. I would personally recommend taking their python course. Python is one of the easiest languages to learn at the moment because it is super popular right now, free, and has a whole lot of support on the internet. When you run into a problem, just google it. Chances are you're not the first. If you get bored easily, I'd recommend thinking of a little task you'd like your computer to do and writing a script (code file) for that. Maybe you want to have your computer give you the weather, or maybe there is a value you have to compute a lot, perhaps make a simple game.
For python I recommend the Ureka bundle (a python friendly terminal and easy access to useful software) which you can download here. It's astronomy-centric but very easy to install and use. If you use the online course, you do everything (writing the code and running it) on the website and won't need that. If you tinkering on your computer with code, try TextWrangler. You can save text documents there with the .py extension and it will automatically color-code things for you.
If you feel overwhelmed by python, you can learn a lot of the logic behind programming using Excel or Mathematica. Keep in mind that there are many languages you can start with, so if one doesn't click, try another. I personally found Ruby-on-rails confusing as hell, and couldn't get C++ either* but when I had to learn Fortran and Python simultaneously it was like I was suddenly a polyglot and could make sense of any programming language thrown at me.
* Weirdly no one could explain to me why it needed to be complied... "Compiling" is just turning the C++ speak into computer language (binary) for anyone else who can't get a straight answer...
(Also: here's an astronomer's cheat sheet on how to get started with python)
More on Astrobiology
Sort of curious but want to learn painlessly? Videogames like Spore and RNA have a lot of astrobiological concepts in them. Personally, I notice a lot of things in the Mass Effect series that play off of it (extinct life and fossils everywhere, and that homo-chirality thing that makes some species unable to eat each others' food is totally real and possibly comes from the polarised light of the sun their home planet orbits FYI in real life eating the wrong chirality doesn't always harm you, sometimes you just "pass" it). The ideas in a video game or fiction book might be "polished" to allow for artistic license, but there's a lot of allusions to real science within them. Similarly, once you start learning about astrobiology you'll notice little things in sci-fi movies and tv shows alluding to it to like silicon based life in Star Trek.
Also consider watching nonfiction series like Carl Sagan's Cosmos. He is the most painless speaker to listen to.
Just want a little more info? Watch the ESA's introductory video
Prefer to read? I highly recommend Carl Sagan's books (all of them... go to the library). He makes things super easy to understand without talking down to you. I also recommend "Rare Earth" by Brownlee and Ward and "Here be Dragons" by Levay and Koerner to see the arguments for and against life or intelligent life being common.
Super keen and wish you could just take classes already? Take a free online course