Too old???
Age has nothing to do with getting through the courses. Commitment and desire will almost certainly carry you through. I was 42 when I went through the NATS course at Bournemouth and today I am an Assessor and OJTI.
It's not really a job but a vocation. Be prepared for lots of hard work as the learning curve is very steep. If you want it enough you will get through.
At the moment there is a huge shortage of controllers. You may even be approached by an airport whilst you are on the course, offering you a job on completion. It has happened.
Good luck, but don't leave it too long.