Considering a 35mm prime but not a 18-35mm lens because it's not a big enough range seems a bit lol
Prior to having my 18-35mm lens, I had the canon 40mm stm lens and whilst I liked it, as Janesy mentioned, the focal length just wasn't that useful. At least with the 18-35mm you get a pretty sharp 35mm lens as well as 18mm and everything in between. I used the 18-35mm more in the first few months than I ever used the 40mm :\
The new Canon EF-S 24mm pancake could be worth checking as it's a better focal length for crop sensors but only F2.8