There are several important points to mention.
First, you need to check the Charger for your IPhone to ensure that it's designed for "world operation". Look for the phrase Input Voltage 100-240 VAC, 50/60 Hz. If that's the case, you'll only need inexpensive Plug Adapters to operate in Europe.
Next, Plug Adapters. The U.K. style has three large rectangular pins, while the style used in continental Europe has two round pins. I'd suggest packing two of each type (they only cost a few dollars each).
The most important point to make is that you'll have to be VERY careful about using the data portion of your IPhone (E-mail and web surfing) in Europe, as data roaming charges can be extremely expensive! You might want to speak with AT&T to get details on any plans they might have that can reduce these charges somewhat. Many travellers using IPhones disable the data portion of the phone and just use it with Wi-Fi (where hot spots are available). I've seen reports of traveller's who return home to find a $3000 bill waiting in their mailbox.
I also travel alone and like to keep in touch with family. I use text as it's about the cheapest method. With my plan, outgoing texts are about 75¢ each, while incoming texts are free. I just use a basic "flip" Cell phone (nothing too fancy) but it works fine. If your parents also have a Cell phone, that might be an option to consider.
Good luck and happy travels!