However, take the info with a pinch of salt... the info on the web site seems very basic to me, if you want to go via route 4, you could also join the RN; then, later, you do not HAVE to go via route 2, you could receive a scolarship from NATS, OR pay your own way.
Personally I would say if you want some adventure before growing old, try the armed forces first, but beware, the actual ATC job is very different from civil ATC and the transition is not always straightforward, nor easy. You could be the best military ATCO and struggle with the Civil courses, or vice versa.
To get a balanced view, look at as many sites as possible, for instance the RAF website (the RAF and Navy run a joint ATC school at RAF Shawbury, in Shropshire), and also the NATS website. Also try looking further afield to Europe etc.
Whatever you choose, good luck!