Whilst it's not exactly a credit card, I would definitely recommend using a Caxton card. You can get one or all of 3 types, Global Traveller, US$ and Euro cards. You pre-load these, the GT with sterling, the $ and Euros at favourable exchange rates, and can withdraw the equivalent of £300 maximum per day with no ATM charges.
You can choose how much you want to top up anytime via the internet and all you need to do to open an account is pre-load £10 which is automatically credited to your card.
I used one of these traveling overland to Australia and it saves a whole lot of currency exchange hassle with no ATM charges. I will be taking a EuroTraveller card with me to Spain which you could pre-load yesterday at nearly E1.18.
Not trying to promote this, but you will find it a really useful addition to your credit card. Have a look at
http://www.caxtonfx.com for more information.
John