2 Weeks divided between Efate and Tanna

Hi we are planning on going to Vanuatu for 2 weeks in August. can anyone please recommened how many nights to spend in Tanna? we want to see the volcano (and stay on the east side of the island the night we see it), a kastom village and snokel on the west coast/blue hole area. how many nights would you recommend staying there and any thing else we should do? thank-you.

I'd say maybe 3 days on Efate and the rest in Tanna! :-)
Unless you want a high-class resort, which is more readily available on Efate.