Emirates have announced that they will be, from the 1st December 2015, increasing their flights direct into Phuket by 4 per week.
Phuket is a minibus or ferry (depending on your landing time) away from Koh Lanta. So these flights might be worth looking at if you are coming over this High Season.
It may also be worthwhile, discussing with us, before you book the flight times, so that we can advise you on the best transfer choices for you. Send us an email and we will give you our best view on your options (firstname.lastname@example.org).