CAP778 should give you the info you're looking for.
Your "problem" may be linked to the autoplot itsself.We had a problem at Maastricht where some autopilots would overfly the waypoint (GRONY) before turning (to GREFI) and others would anticipate the change of heading (in this case 70°). In the Upper Airspace, at cruising speeds, it was a much bigger problem to us as there were danger areas on both sides of the track. In this case the difference amounted to several miles.
BTW It's a "Procedural separation" so the distance between it and a conflicting one should be Lots.