Currency: Scotland uses Pound Sterling (GBP) but besides the Bank of England notes there are also three sets of Scottish issue bank notes, from Bank of Scotland, Clydesdale Bank and Royal Bank of Scotland. These are the most common bank notes in Scotland - but businesses in others parts of the United Kingdom sometimes (wrongly) refuse to accept these. Although most businesses in Scotland accept card payment, there is sometimes a minimum spend (usually £5) meaning that it is good to have some cash. There are also businesses which do not accept card payment at all, although these are quite uncommon.
You can read more about the Scottish bank notes on Wikipedia. https://en.wikipedia.org/wiki/Banknotes_of_Scotland
Bureaux de Change: several places in the city centre offer currency exchange, for example at Waverley Station and some department stores on Princes Street; bring your passport.