How do you say

My friends and I are planning to take a vacation in Thailand, and I heard the beaches are supposed to be beautiful there.

..in Chinese?

我和朋友打算去泰国度假,听说那里的海滩很美。

wǒ hé péng yǒu dǎ suàn qù tài guó dù jiǎ , tīng shuō nà lǐ de hǎi tān hěn měi 。

How do you say "I've reserved a train ticket three weeks in advance." in Chinese?