Diving in Scotland - now there's some coooooooold water. Fortunately, you can load up on haggis before you hit the water. I cede you my share of the world's allotment of haggis.
A used bc should not be a problem, but a used drysuit opens up a whole can of worms. You can spend a lot of Scottish moolah fixing lousy seals and having it resized to fit you. On the other hand, with a little delving around, you ought to be able to come up with something pretty good. Take a look at the Yorkshire Divers board since a lot of them are over on your side of the ocean.
I don't think I'd dive in a wetsuit in Scotland - it would have to be so thick that it make things just too awkward. But then again, I'm diving in a drysuit in southern Florida in the winter.