I posted my application the day before my 18th birthday. I'm now 20 and have just finished Area 2 at the college and am now starting training at LTCC.
I managed to get through everything first time so up to date it's been good (touch wood) but there's still a long way to go.
I was the youngest on my course and as far as I know I'm the youngest trainee at the unit. The oldest on our course was 32 or 33. There are some courses which have had older people, usually with previous experience.
Don't let age hold you back, go for it