Hi!
I went to England (London and Bath) and France (Paris) last summer (early August). Here were some of my observations:
-I felt very out of place in sneakers, and someone did mention that Americans (or Canadians too, I'm assuming!) were easy to spot because they wore sneakers. I ended up buying some cheap ballet flats at H and M in paris because I felt so out of place (I joke about that being my fancy-pants shopping trip on the Champs de L'ysee). My metallic sandals that I brought would have been fine but it was cold and rainy, and all I had besides that were my gray new balance tennis sneakers. If I did it again, I might try bringing something like some low cut converse, or pumas, with gel insoles added.
-The weather was much cooler than I expected. I'm guessing it might even be more so for you in Scotland. I brought skirts and shorts, but ended up wearing my one pair of long pants (dark skinnyish straight leg jeans) almost every day. They also made me look less touristy than my shorts would have, I realized, and were warm!
-I ended up wearing a light gray scarf almost every day too...something about a scarf in Europe feels so right!
I'm sure you'll look great in whatever you choose, just passing on some of my notes! Hope you have an amazing time!