There are no wasters - sorry drug addicts in the army already. The CDT is already struggling with the amount being caught, I do believe infantry battalions are even setting up rehab platoons. I know the Support Corps are taking a less tolerant approach where they would rather be undermanned than deal with addicts.Changes to basic training would probably sort out most of the 'thick as a castle wall charv' - esque people; you would be surprised what a short sharp shock can do to most people's lives.
Moreover, if you get them young before they really have a chance to turn into utter wasters then the army would have an easier job; just because the existing system doesn't lend itself very well to my proposal, doesn't mean an improved one wouldn't.
If the army is expected to deal with the problem of the giro culture then perhaps Bad Lads Army leads the way - use ex soldiers who are of a DS (Directing Staff) mindset and put them into secondary schools.
It would help to keep ex soldiers in employment and deal with the chav world. Perhaps a slight manipulation of human rights to bring back stress positions, don't need corporal punishment to deal with them, but I know an hour a day on a parade square would certainly help to bring them in line.
Drill is a pill and should be taken twice daily.