If you want to study in France, knowing a certain level of French is important as this can help you in daily activities and communicate with the locals. However, French language proficiency will not be mandatory for most English-taught courses. In any case, checking this with the university of your choice is crucial. On the other hand, many Irish universities ask students to submit proof of English language proficiency as part of their application process. Thus, you may need to attempt tests like TOEFL/IELTS.