It would be naive to say that Flybe won't take anyone other than from their MPL course given the leadtime involved in training up people coupled with the dynamic nature of the industry which so often necessitates bums being on seats at short notice. Having said that I don't see Flybe recruiting anything like the numbers they used to from the old integrated/modular routes.
With rumours that FR will start training in house in the new year this puts both of the traditionally biggest recruiters of low houred wannabes looking quite differently at the product they require. Your guess is as good as mine as to how this will all pan out.
My advice would be don't go to a school just because it advertises a "relationship" with Flybe or any airline for that matter. Go there because of the quality training and reputation in the industry. If it can get your CV onto the right desk then by all means its a bonus but nothing is ever guaranteed in this industry.