Fairies visit other worlds regularly and have been known to deputize for the angelic squad, when sending them in would be considered too frightening or a case of overkill. Eileen is the only one who wants to stay on earth though! Fresdian (Rose) comes to love life on earth (though naturally it’s the wildlife she’s most interested in).
There is no question of the Kingdom having its own “space programme”. Any world the Kingdom wants to visit, well it sends representatives and usually the world in question does not realize. Another reason for the lack of interest in other worlds is the Kingdom has been at war at some point with practically all of them! And most in the Kingdom relish the relative peace and calm now and don’t want anything rocking the boat. If that means ignoring the neighbours, so be it.
So how do your fictional worlds related to others within your equivalent of the solar system? Equally if you write about the one world only, is there any thought within that world of seeing if there are other universes to explore? Does your world look outwards or inwards?