I assume you will move to Montreal, as that where mostly all English school programs in the province could be found.
Here it is a list about every English program in Montreal, by the English Montreal School Board.
Although the amount of places for English speaking students have been capped in the province recently as a new law have passed.
Besides that point, you can't just enroll them in an English speaking program, you must check and apply for a "certificate of eligibility" if you are going to enroll them in a public school. You can start from there, applications are processed within 10 days . If they are not eligible you should think about private schooling or just a French school, some have integration programs that could ease their time living in Quebec.
Regarding what school to go, as in ranking, it is dependent on where do you live, as you can only attend a public school that is in the same district as you, with rare exceptions to that (usually you are put in a waiting list). These are the districts covered by the Montreal English board.
Côte-Saint-Luc, Hampstead, Montréal (except Lachine, Lasalle, Pierrefonds-Roxboro, Verdun), Montréal-Est, Montréal-Ouest, Mont-Royal, Outremont and Westmount
