The International School you called, it is officially called International Baccalaureate Program (IB). In Canada, it is offered in regular schools that are members of IBO.
As well as I know, IB program is only available in High School in Ottawa, but is available from grade 3 in Gatineau.
The school offering IB in Hull is Ecole Mont-Bleu. It covers Hull/Aylmer/Chelsea sections.
You have to be a Quebec residence to send you child to that school.