Here you will find cable and wire for connecting lighting. H05VV-F installation cable is available per 10 meters in 2 or 3 cores from 0.75 to 2.5 mm². VD wire (H07V-U) comes on a 100-meter roll in brown, blue, black, and green/yellow.
You will also find ready-made connection cords with a Europlug, fabric-covered cord, and Wieland cables. Unsure about the thickness? For a single lamp, 0.75 mm² is enough. If you are routing a circuit through a meter cupboard, 1.5 or 2.5 mm² is usually used.