The Army is(or at least was) slightly different. When I did infantry training, those going to become bandsmen still had to complete the full 18 weeks training, not just the 6 week CMS(Common Military Syllabus).
They then went on to whichever School of Music they were designated for. Drummers however are recruited from within the ranks of an infantry unit and a Drums Platoon would specialise in support weaponry in a combat role i.e. GPMG in the Sustained Fire role or similar.