Hey
I can tell you from experience, it is never too late. I have no knowledge of anything that i "should" have learnt in year 11. I can tell you that it wont have much effect on any subject apart from mathematics. Mathematic is probably the only course that requires you to use the logic that was taught to you from year 8 and so on. It all depends how you think about it, the thing that helped me the fact that if you want to act like a man you should do this. Putting it off and lacking off is a sign of weakness and immaturity. Also it depends how bad you want to do something with your life. If your expectation is to be a Apprentice then you have nothing to worry about, but if you want to achieve something then you have to work for it. Nothing great in life can be gained without hard work.
I like many others in my environment did not pay attention to this, and as a result i jigged ALOT of year 11 and begining of year 12. I could see the effect this had by simply looking at my exams, but yet still i told my self "ah i swear im gonna study from now on" but as many do its a psychological thing to say to overcome your failure.
The Thing that changed my perspective towards school was the time i spent at home due to my gland fever. You just have to realise what you want from your self and if you would be happy doing that. And Most importantly it seperated me from the people who lowered my expectations. Seperating you self from people who's ambition is to work with bricks and etc.. (not trying to offend anyone, some people enjoy these things) is the best thing you can do to allow yourself to understand what it is that YOU want. Its stupid but it does effect you. If everyone around you speaks with low goals such as "man dont worry about the hsc, have fun, their is always another way like tafe" will make you think hey their right you know, it doesnt matter. But in reality it does. And if you think you can get anywhere with tafe, trust me you cant. Tafe does not give you the skills to be at the top.
Sorry ive spoken to much. But ill just use this as an example. I personally "slacked" off in year 10, 11 and most of year 12 until term 2. But then i put a stop to it and tried. My english ranking was near last (87/92) but i changed this in a matter of weeks to what i am now which is (15/92). It made me realise i can do anything. My Physics teacher said and i quote "With the ammount of times you have been to class in contrast with your mark, i think you should have gotten 100 if you came everyday".
My advice is to you is to find out what it is that you want and be a man about it and get it. Its one year and although it may seem long, trust my words, It is one year which could change your life, but the outcome is always in your hands.
Amin