The British currency is the pound sterling (£), with 100 pence (p) to a pound. 'Quid' is the slang term for pound.
Three Scottish banks issue their own banknotes, meaning there's quite a variety of different notes in circulation. They are legal currency in England too, but you'll sometimes run into problems changing them. They are also harder to exchange once you get outside the UK.
Euros are accepted in Scotland only at some major tourist attractions and a few upmarket hotels – it's always better to have sterling cash.
Hotels One pound per bag is standard; gratuity for cleaning staff completely at your discretion.
Pubs Not expected unless table service is provided, then £1 for a round of drinks.
Restaurants For decent service 10% and up to 15% at more expensive places. Check to see if service has been added to the bill already (most likely for large groups).
Taxis Taxis are expensive, and locals rarely tip; generally rounded up to nearest pound.