A little over 10 years ago AOPA, supported by GATCO and the RAeS suggested to the CAA's SRG that civil flying training schools adopt the military R/T call-sign prefix "Tyro" to indicate to ATC (as it does in the military) that the pilot is a student and thus inexperienced
I think it's safe to say that most controllers already know who the inexperienced pilots are, just by the way they use the r/t and the equipment flown, they learn to have a certain suspicion about wayward pilots. I think in the US we were required to identify ourselves as a student pilot.