When I did my 6129, I remember going for the first practical and booking first test etc, and I was anxious, but you'll soon relax and get into the swing of things and get to know what they're expecting of you and how you need to be thinking. To be honest the course is quite easy if you're prepared to put the time in and be committed to it. The real work starts when you pass and have to move on from there, you learn way more in the real world, but you do need the underpinning knowledge before you start in the real world. I've been out on my own now for nearly 18 months since I passed my 6129 and I can honestly say I love my job and am out 7 days a week whatever time., day/night and am so busy at the moment.If you want to progress after course I think you need to bend over backwards to help customers out. Be helpful, polite and respectful and turn up when you say your going to and clean up after your job, it will go a long way. Try to get on with manufacturers courses to get a better insight into things, last week I did a Valliant course on ground/air source heat systems and solar.
Good Luck and you will make of it what you want to with the correct attitude and dedication.