ATCO123,
The information is all in this thread. Everyone will have a similar response here; read the last 100 pages and you'll find a huge amount of information to digest. If you have any more specific questions after that then people will typically be very willing to help. The NATS website itself is also a very good place to start.
Others have made the suggestion that we collate the most essential parts of the information for a separate thread but at the moment this isn't the case.
All the best when you decide to apply.