Copied from the Bank of England Website:
Under section 18(1) of the Forgery and Counterfeiting Act 1981 it is a criminal offence for any person, without the prior consent in writing of the Bank of England, to reproduce on any substance whatsoever, and whether or not on the correct scale, any Bank of England banknote or any part of a Bank of England banknote. The Bank of England also owns the copyright in its banknotes.
I'm pretty sure the law will be very similar in Scotland!