Was on Efate for a week at the beginning of October. Windguru forecast 16kt average for the week so took over my 12m just in case. Ended up that average meant mostly too light for me 13kt, with only occasional periods up to 18 or so. Airport has a live wind meter you can check but it's not really indicative of the wind on the coast. Direction was also just off for Mele beach most days (they were out on 14m kites the day before I arrived). Possibly the north side of the island could be kited if you got a ride there and don't mind kiting the reef. Be aware though a lot of beach locations are just washed up coral with minimal sand so makes launching and landing interesting unless you have a helper. Tides are also important with both the reefs and a lot of lagoon coral exposed at low tide.
All that being said I did get a few hours in one morning before a storm rolled though and killed the wind. Got a quick lift in a boat out to a little island off Eratap resort that had some clean wind and kited mostly inside the reef there which was ok. Good swells out past the reef which had a messy dumping right hand break. Tried taking a kayak with my gear out there another day but the wind died off by the time I got there. 15m so would have probably been ok though.