I suggest the 40 as well. Small, fast enough, light, great image quality.
A warning about the 10-18/22mm range. Shooting this wide (10-14mm on apsc sensor) is challenging stuff. It's less about "getting it all in" than it is about maximizing those wide characteristics to accentuate foreground content. You can create a lot of far-away feeling, uninspired images with an ultrawide. That's why I've chosen a simple 20mm for full-frame as opposed to, say, a 16-35. This doesn't mean don't get one, but it means it's not necessarily a solution to getting great interior or architecture or expansive landscapes. You can take amazing shots with an 18-55 too.
Keep using your 18-55. It can do a LOT. And consider that cheap, small 40 or 50 prime as a next step. Fix-focal length shooting is also good discipline and can really force you to see and take better photos.