I started on a t3i with the it lens and took plenty of great photos with it. Landscape doesn't always need to be super wide angle. The kit lens will be wide enough most times, but if you really want something wider you can get the EFS 10-18mm or the Rokinon 14mm. The Rokinon is a fully manual lens so no autofocus but that is fine. The 55-250mm you have is actually a great lens for a crop sensor camera and will give you some good reach.
Honestly the two lenses you have are really good for learning.
Honestly the two lenses you have are really good for learning.