Honestly, I don't mean to be harsh but I wouldn't bank on it.
If you've done stage 3 or maybe stage 2 then you might get a course in the next year, maybe 2
If you've just don't the initial tests its going to be a long time - basically until the market picks up, NATS start winning contracts or the next wave of retirees happens.
The fact is NATS have too many ATCOs as it is
I do feel that they should tell candidates this. It's quite poor show to leave so many people hanging in a recruitment process for over a year, especially when the expectation is plastered all over their website is that there are four intakes a year and logically, people shouldn't have to wait more than 4-5 months from the start of their application to the end.
Honestly it doesn't take much...recruitment is a two way street and it's expected of employers to keep candidates updated on the progress of their application and let them know of any delays.