As in the rest of the United Kingdom, Scottish currency is the Pound Sterling (£). Scotland’s three national clearing banks continue to issue their own sterling banknotes (including £1 notes, not produced south of the border). These are The Bank of Scotland, The Royal Bank of Scotland and The Clydesdale Bank. These notes are very common in Scotland, but are sometimes (wrongly) not accepted in shops in England (English banks, however, will exchange them for Bank of England notes). ATM’s operated by Scottish banks will usually dispense the Scottish notes, but bank tellers will cash travelers cheques into Bank of England notes on request. Scottish banknotes may be difficult to exchange outside the UK, where foreign banks are generally unfamiliar with the notes. If in doubt, exchange your Scottish notes for Bank of England notes before you leave the country.
A guaranteed way of getting Bank of England notes is simply to make a withdrawal from an ATM run by an English bank (e.g. NatWest, Barclays or HSBC) although they tend to be found only in major cities.
As Bank of England notes are more commonly forged than their (lower-circulation) Scottish equivalents, smaller shops are sometimes wary of larger-denomination Bank of England banknotes, especially the £50 note, particularly when the note is in an uncirculated condition (as is common with sterling notes sold abroad).
Euros are accepted at a small number of High Street stores and tourist shops, but this should not be relied upon so change your money into sterling.
Scotland is relatively expensive when compared to some other European countries. As a basic rule, the further north you venture, the more expensive it likely gets, mostly because of the difficulty and expense of supply.