Taking in 19-23 cats sounds borderline hoarder the places I've volunteered do not let just anyone come in and foster. You need to go though an intake process. I'm in America and most shelters required some kind of intake process so it's not just as easy as showing up and saying you want to foster, it takes time. Fostering is a big responsibility and the purpose is to socialize animals to make them more adoptable, it's not something you do on impulse.