How widespread is the ability to use Euros in Great Britain?

In the UK, you'll really only be able to use Euros in the very touristy places. Rather than take cash with you, why don't use just use a debit card to withdraw cash as needed? That way, you don't have to worry about finding an open bank to exchange it or losing your cash or anything. Plus, you'll receive a much better exchange rate once you're abroad than you will at home. Check with your bank before you go to make sure your card will work and find out what it charges for using a foreign cash machine.