From context, I think "plank" means "deviation bar". This makes sense as in enroute you'd be able to track VOR and VOR/DME on the HSI. And in approach you'd be able to also track the localiser on the HSI.
Looking at this cockpit picture, it does appear as if there are flight director indications on the ADI as well.

To clarify on Airbus, the FMS has an approach phase that you activate. This changes speed targets and so forth in managed mode. However, to get the autopilot to actually capture the ILS, you need to arm Approach on the FCU/ACP (glareshield autopilot controls).