Other than LV decorative sets, I'd say the most common form of outdoor lighting here is the quartz halogen floodlight. Every other house seems to have one (or more) of these 500W monsters shining down on its grounds these days as a security measure, generally the PIR detector type.

Where 240V is run underground to garden lights, I'd say the SWA cable is by far the most common method for residential. That's the proper way of course -- I see many DIY efforts which involve threading flex through garden hose or sometimes just burying regular "twin & erath" cable. [Linked Image]