7cm isn't tall enough unless you have a minimalist 1970s skirting which was just bullnose shape at my parent's house, ie just rounded off on top rather than square.
Skirting is usually 11cm or higher or 119mm on Travis Perkins from a brief glance.
Architrave is the vertical trim that goes around a door to hide where the door lining (the pieces that line the inside of the door frame) meets the plasterboard.