Telerob
There was a big age range on my course - from 18 to about 45.
There was no discernable pattern of the younger/older guys and girls being more successful.
I started when I was 28 and found the theory workload really tough after 10 years out of education. There is a huge bulk of material to learn.
There always seemed to me to be 3 groups of people as far as the radar was concerned - it came to some very naturally, to some not at all and others had to really work hard at it. The latter were in the majority.
As previous posters have said, it comes to down to determination, ability and application rather than age.
Good luck