It depends on the denomination and group running the school.
If the school is evangelical, your time there is likely to be spent being bombarded with arguments, pamphlets, bible-“studies” etc, designed to teach you that Catholicism is false - not the true gospel etc.
If you are going somewhere like that you had better be strong in your faith for it will be challenged constantly, and you will be presented with selected bible verses designed to “prove” catholic beliefs, particularly with regard to salvation, purgatory, Mary, images and papal authority, wrong. You will also be charged with answering claims and much skewered and even false “information” regarding the inquisition, crusades, actions of medieval popes etc. You will need to study the Catholic response on all these matters.
Other moderate protestant groups can be more open to Catholic belief, but still be prepared for many misconceptions, and false ideas about “Millions” killed by the inquisition, alleged witch-burnings etc.