Use Google.com/maps. Search for the address: Frøvikveien 320, or just Leka.vTo get to Leka you have to take the ferry from Gutvik (mainland) to Leka. You can see ferry routes here: http://www.tts.no/skei-leka-gutvik/ 

The ferry trip across the Lekafjord takes approx. 20 min.

Distances:  

Trondheim: 320 km, 5 hrs
Namsos: 150 km, 2hrs 40min
Steinkjer: 200 km, 3hrs 20min
Rørvik: 80 km, 1hr 45min
Brønnøysund: Approx. 100 km, 2hrs 30min (take the Vennesund-Holm ferry). See timetables: http://www.tts.no/vennesund-holm/category1634.html

Travel time is stated, including the crossing by ferry.

Nearby airports

Brønnøysund, approx. 100 km
Rørvik, approx. 80 km
Namsos, approx. 150 km