"离家外出聚会" 在英语中可以翻译为 "go out for a party away from home"。
其中，"go out" 是一个常用的短语，意思是 "离家出门" 或 "外出"。例如：
I'm going out for a while. 我要出去一会儿。
She always goes out on Friday nights. 她总是在周五晚上外出。
"For a party" 是指 "为了参加一个聚会"。例如：
We're going out for a party tonight. 我们今晚要外出参加聚会。
Are you going out for a party this weekend? 你这个周末要外出参加聚会吗？
"Away from home" 是指 "远离家"。例如：
He's been away from home for three months. 他已经离家三个月了。
She always feels homesick when she's away from home. 她一直离家就会想家。
因此，"离家外出聚会" 就可以用 "go out for a party away from home" 来表示。例如：
I'm going out for a party away from home this weekend. 我这个周末要离家外出参加聚会。
They always go out for parties away from home on the weekends. 他们总是在周末离家外出参加聚会。