Hey there Op, I was in vet much the same boat as you, I left school at 13 and didn't go back until I was 18. I had very low self confidence and was very quiet.
I decided to go to a youthreach, now these places have a reputation of being very rough. Now was there people there that were rough, yes but there were also people like myself, it was a mixed bag and bullying was almost non existant as everyone who went there had a story, we were like one big family. I made lifelong friends and gained exceptional experience and self confidence. It truly was perfect for me. I did an LCA which was perfect to ease me back into education. You will get a training allowance for going to Youthreach which is the same as the dole.
Your other option is VTOS, now you do have to be 21 and on a social welfare for a period of time. It's a good program and I wouldn't worry too much about the ages, I would think the vast majority of people would be in their 20's.
I personally decided not to go back to secondary school as I did not want to be judged, plus I think by the time you get to 5th-6th year you will have kind of made your friends. But if you think you could do well why not?
Best of luck with everything, returning to education was the best thing I ever did, I am now in college working towards making something of myself and I couldn't be happier or prouder.
Definitely do it. A friend of mine went back at 23 to do her leaving cert because she wanted to do a course that she hadn't enough points for the first time around. She was back in her local secondary school with teenagers. She said that at first it bothered her (the immaturity) but she found overhearing their drama to be very entertaining. It was a tough year but she is 100% glad that it was the best thing she did. You have that extra bit of maturity that you know what you want to do and are not just applying for college just for the sake of it. You will have that bit more focus because of the sacrifice that is involved. Best of luck
I know a guy who did his JC at 35, LC 37,...........qualified teacher in his 40's.
If there's something you want to do education wise. Go & do it.
In fact being a couple of years older is no harm.
There's a lot to be said for waiting unitl 22-25 before attending 3rd level.