Best option, Get an IR at first possible opportunity, end of story!!
Why? What if the sort of helicopter work you want doesn't need an Instrument Rating? What would be the point of spending something like £30k on an instrument rating if the nature of the work is all VFR?
Not everyone wants to do North Sea!!
The military guys leave with a military qualification which has to be converted to a civilian licence. So they would have to sit the exams etc. The advantage they do have though is hours.
Cheers
Whirls