first thing he will do when he gets out will be to spill his guts to the media outlet that offers him the most money.
The AB is and will be subject to the Official Secrets Act and 'spilling his guts' could get him a prison sentence, additionally he won't be allowed to profit from his crime, if offences are proven.
A likely scenario is a complete debrief by the RN, charged with being AWOL, charged with contacting the press without permission, charged with any breaches of the OSA that may have already occurred. If found guilty he could be discharged in disgrace or he could be discharged as 'Services no longer required', possibly a short period of detention too.