We don't have experience with pounds but have recent experience with euros. Look up the exchange rate before you go so that you will know if you are getting screwed or not when you have to make an exchange. It changes all the time, but you can get a good idea. Also ask about any fees to do the exchange.
I would check with my bank before leaving. We did not, but I understand that it takes a few weeks to get the euros.
We just got back from a trip to Italy, Austria, and Germany and I found the airport to be the worst place to do the exchange.
In Rome the Hotel we stayed at would exchange US dollars for Euros at the front desk. There were many places around the city that would exchange dollars for Euros, but again I would ask about the exchange rate and fees before I did the transaction.
In Milan, Italy, we found a bank that would exchange based on the current exchange rate with no fees.
In Munich and Austria, we did not see many places to do exchanges.
Never dealt with euros
When I travel I have found some International airports give great rates, Manila Philippines and can handle large transactions and have great exchange rates
I always go to black market money exchangers hopefully in muslims area for highest returns on dollars