hi there!
Upper age limit for sending in your application form for NATS - you have to be under 30 yrs old.
If you are still 29, send the form in now, it doesn't matter if you take the tests when you are 30!
It certainly doesn't matter if you are over 30 when you start the training because I'm 30 in February next year and start the training in October next year!!
Best of Luck