In the UK to become an ATCO be it from an ATSA position or from the outside world you all have to apply the same way - there is no preference or need to be an ATSA first.
The 'sticky' post at the top of the forum has all the gen on whats involved and also links to VectorLine's website which has lots of info for applicants and new recruits too. If its not, I'm sure he, or one of his alter ego's will post it here soon....
Edited as I now know the link to
VectorLine's Website so click on his name to enter!!!!!