has anyone ever had an interview for a job that is too advanced after a traineeship?

They would not interview you in the first place if they didn't think it was a job you could learn to do.

You tell them you appreciate you still have much to learn but you will totally dedicate yourself to the job to become an asset to their organisation.

Be confident. Just remember this; what have you got to lose?, give it your best shot. Worst that can happen is the job doesn't work out and you have to do something else but at least you tried and gave it your best effort. But to progress you have to break out your comfort zone and give it a go and then do your level best to learn the new job in the role. As you advance on in your career you will reach many more crossroads like this, you have to take the advancing path if you are to progress. I have had many anxious moments like this in my own career in the past I can tell you and you have to go for it. You can smash this. Giving up or not even trying is not an option.

Being successful in life is a journey not a destination

Good Luck

as in what would I say at the interview? the traineeship did not prepare me well for the job. I have transferable skills from the traineeship but the traineeship (from the same company by the way) was too simple, this is advanced and the worst that can happen is I don’t get the job, I’m not expecting to. You can usually predict the interview questions from the job description and if they ask anything from majority of the job description I wouldn’t be able to answer.