Honestly, I have both and on your small-body camera the EF-M 11-22 will give you a wider field of view with a lot less bulk. The EF-M 15-45 you have already has a wider coverage than the EF17-40, so you have that covered. The main difference between what you have and the EF 17-40 is the wider constant aperture, but for landscapes you will not normally want to come down to f/4 - you will want depth of field and that means higher f/stop values. However, in order to get that f/4 aperture, the 17-40 is much bigger and heavier, and BTW is not stabilized, while the 1EF-M 1-22 is. If you are visiting Scotland and want to capture the insides of some of the old Kirks and castles, you will be very grateful for the extra width of view of the E F-M11-22. The image below was taken, hand-held, in available light, with the EF-M 11-22 at 11mm, the EF 17-40 would not have got the shot in the cramped area inside.
You can even get great close-up images with the 11-22, because of the massive depth of field afforded by the short focal length, as per this hand-held shot in a park:
Finally a shot taken at a longer focal length with the EF-M 55-200, available light, hand-held
If you had the 11-22, and the 15-45, I would add the EF-M 55-200 IS STM - which can also be useful for landscapes you cannot otherwise reach. There is a common misconception that landscapes are best shot with wide-angle lenses. Sure, they are used for that, but it is also an advantage to be able to reach across a valley and capture something further away, and then there is the wildlife, and taking portraits.
One thing you should consider taking is a small, light tripod for those occasions when you need a slower shutter speed - again, inside, but also for low light shots like sunsets and the blue hour after the sun has gone down. With the lighter lenses of the EF-M series you can reduce the bulk of the tripod itself as the weight and balance of the camera will both be more suitable.
I don't know how you currently hold a camera, but the best and correct way to do so is as shown on the attached image. Holding it to your eye and using the EVF will give you much more stable support than at arms length looking at the LCD. There is a reason tripods have 3 legs and not 2. The eye contact to the body of the camera gives you that 3rd point of support. That will make your shots much steadier without using a tripod.
If you are not sure, rent the gear and see for yourself. I assume a trip to Scotland is not a cheap or an experience you are likely to repeat soon. So, getting the gear right before you go is definitely worth the effort. Once you have bought your gear, practise with the camera, lenses and control - especially the latter, so that you don't have to think about where they are, otherwise the camera will get in your way and slow you down.
