If you have been offered a Commission in the Royal Navy for whatever specialisation, you have done exceptionally well and this chance is unlikely to repeat itself. All RN Officers (with a few exceptions) do the standard year's basic training at Dartmouth. The course is gruelling and you are expected to be physically fit. Specialisation training comes after that.
I'm not clear on how long one currently has to 'sign up' for, nor on the process for getting a 'permanent commission' but many Lookers rise to high office in the RN, even above ship command. The Admiral (Flag Officer Sea Training) handing out pilots' wings recently, is a Looker. The current head of the Fleet Air Arm is a Looker.
I'm concerned you might be thinking too much. It doesn't do for the stick-monkey to think too much. He needs his brains to understand what his Looker is telling him.
LFH