Wa bus-3rd sia. During my time a few years ago, is sgts ask men to go back wash up, they offer to wash themselves leh. Of course us men can't just dump them to do themselves too right? Everyone wants to clean up and faster gaodim, go wash up and go rest. Btw Armour sgts no time to lepak one. Need to account for and clean heavy weapons and vehicle equipment too.
If he got posted directly (i.e. mono intake) to an Armour unit, then most likely he'll stay in that same unit for his whole NS stint, even after his POP. And yes, Armour units will most likely be sent overseas once or twice for trainings/exercises, however not overseas deployment. Max 3-6 weeks only. Besides, if it's somewhere like Australia and your beau has free time, he can either use internet kiosk on camp site or mobile reception to contact home.
Btw you'll gradually cope with parting with him for longer periods as Armour units tend to train over weekends for long exercises (personal exp) due to training grounds being booked by other units for weekdays. Regardless if it's different now, what most likely remains is that he could be away for 4 days without any contact home.