There is a big difference between license and non-licensed duties. This will become obvious after just a few weeks of training. You have all you need to move on to the next level. I started a license class last March with 33 months of NLO time and can see that the NLO experience will be very valuable to me, but not in the ways you might think.
Your first test will be the GFES. I made a 96 on my GFES while suffering through a kidney stone for the June 4, 2008 test. Only my test preps saw me through that very tough time. If I were you, grab the GFES prep material now and learn the concepts before you leave for class. I know you will have plenty of backshift nights with nothing to do but look at the material.
When and only after you have learned the concepts look at the test bank and old tests from the NRC website. Drill yourself till you can't stand to look at it anymore. Take the old tests under test conditions a few times a week leading up to your test date. The mental effort I had to put into taking the GFES test felt like it did not exist. I had drilled (self study) so much that I just knew the answers by reflex without much thought. I could explain the theory etc to you if asked, but that never even crossed my mind during the test. I just "knew" what the correct answer was. This system seems to have worked well because my class GFES average was about a 93 and they did about the same thing as me.
Systems training is different. I have studied the TS design basis material, system descriptions, all the stuff in the OPS drawings, the control room layout/indications & switches, and procedures. This gave me a high score of 92.5% on my last test (87% overall average). You have all you need from in the field as a NLO.
I am now finishing up my systems training in my class with a big advantage over my engineering peers. As a fully qualified NLO I know plant locations, important valve info (location, how it works, how to take manual control over it), where the piping in the plant goes through etc. In my JPMs I will still have that edge, but that is about where the gravy train ends.
You still have to know command/control of casualties, prioritize problems, and operate the plant with limited information in a safe manner. You will feel almost like a robot with the methodical way you are expected to act in dealing with a list of problems thrown at you.