The best for you is to get a phone as soon as you get to Europe, that is a SIM card.
You have two options: Either you buy or organize a new phone in the US before departing, Tri-band, preferrably. Some companies offer you the phone if you extend your contract by one or more years.
As soon as you reach Europe, get either prepaid SIM Card or a one year package and switch the SIM Card. You can then send SMS to everyone with your new phone number and reduce the costs dramatically.
Second option is to get a phone in Europe and either prepaid minutes or a package. Make sure you get a tri-band so as to be able to use your phone when back in the US.
Some links:
http://www.findspot.com/pay-as-you-g...es-england.htm
http://www.adviceguide.org.uk/index/...ile_phones.htm