I found some weather info here for you. It also has some other infor which you might find useful.

Have visited Khao Lak late Feb/Early March (pre-tsunami)...weather was great...its only an hour road transfer from Phuket airport so weather wise is pretty much the same. Remember that Khao Lak was the region in Thailand worst hit by the tsunami so might be worth getting as much info with regard to your hotel and its surroundings as possible. The region is in recovery hence the good price you seem to be getting for what is high season in the region.

I have visited Phuket this March and evidence of the tsunami was hard to find.

we are now looking at Phuket, the Patong Merlin hotel flying out 14 Feb. This is for B & B is the food & drink as cheap as everyone says it is? has anyone stayed here or anywhere else in Patong?

Eating out of the hotels is cheap....watch the hotels though prices for food can be reasonable but they do hit you on the price for drinks. Its standard to get a minibar fridge in your room we always fill this with drinks from the supermarket.