同學圍毆我,如果打傷了同學,要不要坐牢

That will depend on the nature of the case. First at all, did the police arrive during the incident take place or did they ever contact you after that incident happened? Secondly, did your teacher or principle or your classmate(s) call the police? if the answer is "NO", you therefore are not under any lawsuit. If you are not being charged, how the hell do you have to go to Jail??? OF course not!!! Even if you are being charged by the police or your classmate has filed a lawsuit against you, it didnt necessary mean that you have to go to jail!! That will depend on what criminal codes that they are charging you!! If they have caused a serious body harm, meaning they are suffering broken bones, internal bleeding, etc, you will probably receive from minimum 6 months to maximum two years of jail sentences. However, this would not apply in your case. According to your statement, you have only kicked them few times with your leg. That means they have not suffered much of the injuiry. If they are suiting you in court, the most you will be getting would be probation sentences, or 100 - 280 social community work hours, or HK$500 - 2,000 dollars fine. But like you said, none of the police are involved, so I assume the maximum you will be getting might be some plenalty such as suspension or 缺點, 小過 or 大過from you school. So do not worry!! and dont fight any more!!!

假如出於自衛性的情況, 殺了人都不用坐牢. (記得是對自己十分危險的情況)
假如你沒有預謀當時有意傷人, 上到法庭對你很有利

不至於那麼嚴重!因為是自衛!有逞罰但不會到坐牢~要強調......是自衛

普通唔會，如果比老師發現可能會記缺點見家長，但係如果個個同學話比家長聽，家長又覺得嚴重，佢可以報警，要唔要坐牢，就睇下件事。