How do you say

I plan to go to Hainan Island on holiday in three months.

..in Chinese?

我计划在三个月后的假期里去海南岛度假。

wǒ jì huà zài sān gè yuè hòu de jià qī lǐ qù hǎi nán dǎo dù jià 。

How do you say "This will last for another two months." in Chinese?