I did not know this. I might have to look into this for flying back in the fall.
1. Dayquill/NyQuil because they don't sell it here. The plague has been going around and I miss these things
2. Laptop/electronic things: buy them in the US before you come over, it's cheaper. I would also bring a decent unlocked phone and get a pay-as-you-go simcard
3. Stethoscope....Littman sells nice ones, buy them in the US before you come as they will be cheaper
4. Three ring binders. This is a personal hatred of mine, but the UK uses 2 ring binders and 2 ring binder paper. I don't like it, wish I brought over a years supply of stuff.
Other than that, clothes and stuff. I came out here with one checked bag, a carry on and a backpack. Water proof warm coats are a must for you Scotland bound folks.