This is an age old thread (so I applogy for responding to this thread), so i'm not sure what the OP ended up doing, with previous advice given. Whether he quit or completed the apprenticeship or not. Which ever the case I hope he made the correct decision for himself. Whether he stuck it out or quit.
But with that said for anyone else in similar posistion as OP was 5 years ago, I would like to point out no job is worth its money if its only going to make you misserable and affect your mental health. If you worry about doing this job (or any job for that matter) and it starts affecting your work performance and your function in daily life outside of it, then there are clear sign that this job is not worth your time and mental well being. So in some cases the right course of action would be drooping out/quiting, If you are still in school and you have not signed with any company for the training part, you could always change the course of study. But if you do so, check what rules you school has when it comes to drooping out/changing courses. They will tell you where and when its best to make your changes as drooping out in the middle of semister can affect whether or not you are being re-admitted next semister. IF you have signed for the apprenticeship with a company just re-read the contract and check date you signed the contract and that should tell you the best course of action. If you are just few weeks in, you might want too start filling out the cancellation papers, give reason why you are quitting and have al the correct inviduals sign the cancellation papers and with that your apprenticeship contract is gone for good. However if you have very little left of yourt apprenticeship contract you might want stick it out and complete the program.