The descriptions of schools on this website give the age range of pupils, and the mix of day and boarding pupils, and of boys and girls. This should start to give you a feel for the school. Is there a strong boarding community? Is the school really co-educational?
You can learn a great deal about a school by observing the relationship the pupils have with one another and, when you visit the school, with you. Do they reflect the impression you have of the school? Find out what they do and do not like about the school. What would they change if they could?