I am not a submarine officer but have several friends who rose to the top in the submarine service I admire your ambition
Suggest you take one step at a time there are a few hurdles to overcome before joining submarines
Have you been to the submarine museum at Gosport ? If no then make it a priority
Look on the web for details at
http://www.rnsubmus.co.uk/general/intro.htm
Learn to love Scotland especially Helensburgh You will spend a lot of your submarine service time based there
Are you good at mathematics ?
Can you do mental arithmetic ?
Do you have a scientific background ?
a) Visit your local RN careers office to find out more about officer careers
b) Ensure you have the necessary education qualifications to become a naval officer
c) If you have the time apply to join and spend time in the Royal Naval Reserve you will then find out whether you have the aptitude for the Navy and most important of all whether you like the naval life
d) You need the education and the ability to pass the Admiralty Interview Board
d) Then you have to complete your initial officer training and pass out from Dartmouth
see this site
http://www.britannia.ac.uk/britannia guide for young officers.htm
e) Then complete and successfully pass your continuation professional naval training
If you have proved that you have the necessary qualities you may then be selected for submarine training
If you are successful in the above you can then go to sea in a submarine and in performing your duties need to show your aptitude for command and suitability for promotion
In order to command a submarine you need to pass the Commanding Officers Qualifying course known as “The Perisherâ€
see these sites for more info
http://www.chinfo.navy.mil/navpalib/cno/n87/usw/issue_18/perisher.htm
http://www.google.com/search?q=submarine+command+the+perisher&btnG=Search&hl=en&lr=
There is no quick and easy path to submarine command Hope this gives you some ideas
There are many others who have trod this path before hopefully they can add their contribution
Good luck