What gorgeous ponies - I do have a liking for my natives, having Dales and Fells, and quite often we have Highlands in our classes at shows.
I find my ponies are slow to mature, and are usually 4 before I back them. They seem to carry on growing up and out until they are 8!!
I know two ladies who started to ride at 50, and now have their own Dales ponies .....and one lady came to ride my ponies, and after she got off she told me she had ridden as a girl, and was now 72!!
So, no in my eyes, you are never too old to enjoy riding. Look round at riding school prices, some do good deals, and maybe block bookings.