I have no idea what your company SOP's are about transitioning to and from flight levels, but the Three companies I have been in all have the same rule, When you are given your first flight level by ATC you set standard and when you are given your first Altitude you set QNH. I was also taught this when I did my IR.
This way you never have any problems and yes, I find this works all over Europe and even in non radar controlled Africa, which I have had the pleasure of flying in.
It is only a problem if you make it so.
In EPWW AIP it's cleary stated, that you should stick to QNE until passing transition level. Exactly as in ICAO doc 8168, with one exception - ICAO says, that when you are
cleared for approach and in continous descent, you may switch to QNH immediately. I presume it's not common to be cleared for approach while flying well above TL... Is your SOP against ICAO rules?
But maybe in fact it's not so critical. We all know that the whole idea of flight levels was designed to simplify things during level flight. But anyway, does your company SOP have precedence over AIP of the FIR that you're currently flying in?