How about introducing commentary on the DSA test?
I'm not talking about getting the commentary up to IAM/ Rospa standard (should I be?) - but once the basics of car control are covered, building up the commentary with the drive could be done. That could work for the examiner, and also for the instructor, to point out where they're going wrong before anything comes of it - "what about a scan to the left", for example.
A secondary benefit would I think be an improvement of the driving. I know if I'm a) driving somewhere with a bit of pressure [given news about a family death and needing to get home, etc] or b) having one of those off days*, if I start even thinking a commentary, without actually saying it out loud, it gets the focus back onto the drive.
I think by building it up, it'd be less alien to a learner. It's quite different, introducing the idea of commentary to a driver still in the initial mould, as opposed to even myself, who had previously just got on and drove, without having to put the thought process into words.
*by off days, I'm referring to that previously mentioned by TripleS, among others. That where, for no real reason, no pressure, no tiredness, everything's just a little sloppy. Maybe gearchanges are a bit jerky, you're missing the odd observation, etc. I know I get them, and as I say, trying to put a commentary together gets the drive back on track.
As always, this is IMHO. For once in my life, my tongue is qutie far removed from my cheek, however.
"There's always another day, and I would rather miss a few than get one badly wrong." - TripleS, on overtaking.