I'm about to turn 34 and starting a course this September. Once of my closest friends was about my age, or a bit younger, when she first started teaching (French), having completed her course (a degree equivalent - this was the 1980s) in her early 30s too. Then at 38 she undertook a BSc in Psychology and is now retired but Invigilates AS Psychology exam papers for a bit of pocket money. As she said to me and I'll pass on to you, we're still whippersnappers! (Just not as energetic whippersnappers as 20-somethings...)
I actually think it must be better to be an older teacher in Secondary education because I still remember the awfully hard time we gave our very young teachers at school and would hate to be in that position myself.