if you say "独学" to Chinese people ,I think few people can understand it at once, some one maybe coule guess the meanning when they have seen the Character. “己学”="ji xue" ,it is in common with "独学"。 you can say "zi xue,自学(self-study)" in Chinese,it is from the phrase of "zi ji xue xi,自己学习"。"zi xue" is in common use . I wish my reply can help you, and have a fun in learnning Chinese.

独in Chinese emphosize one person, and 自emphasize oneself. That's why we say 自学in stead 独学 in chinese. 自and己both can mean oneself. mostly 自can modify the other words,eg.自行车,自动扶梯etc. but己can be as a subject in acient times,seldom used to modify the other words. so you can see it in some idioms by it self,such as 己所不欲,勿施于人. Hope I make it clear to you.

自学

自学更贴切吧。

"self-study" is not "独学".It's “自学、自修”。