Hi. Look, I made exactly the same decision to depart from the RAAF during officer training. I don't know what CTC is but it need not be the end of your flying days.
I went for airline interviews a few years later. The best advice I can give is just be honest and tell them you left. At my first interview I tried to cover it up by saying that I chose not to pursue the airforce after being accepted (making it sound like I didn't start). I got a bit of a grilling because it obviously made me uncomfortable.
Years later I went for Qantas interviews and just said "I didn't like it so I left". This went down much better.
So you left. Aviation careers are an evolution. Good luck.
I have just read the CTC post and now know what it is. My advice is to say I want to be an airline pilot not a RAF pilot. I can understand you thinking this may stop you in the future because I felt exactly the same way. Believe me - it will not unless you let it.