I too have a nephew currently going in to the (UK) army, as did his older brother about 5 yrs ago. Judging by the exhaustive enquiries they both underwent after recruitment but before even basic training, including checks with their GP and places of education, I would expect the army to "weed out" your nephew's case even if you did nothing.

Recent reports are that our forces are getting the big rush of would-be recruits which traditionally accompanies an economic downturn, and are currently able to pick and choose only those who precisely match their requirements.