You can use your phone in England but you will have to determine what functions you want to be able to perform.
What you want to do with your phone while overseas will determine what you need to do to make it happen. There are basically three options.
1. Leave your phone as-is. This will let you use free wi-fi all you want with no hassles, where it's available, but any other services such as actually making a call or using data my cost you a small fortune. Check with your carrier about these charges. This is the plan I went with on our trip to Ireland. I wanted to see what the limitations and ramifications were so I could give sage advice for this trip. I missed not having the internet or maps available any time I wanted and I'll opt for option 2 below for this trip.
2. Have the hotel direct you to an electronics store that sells SIM cards. Temporarily replacing your SIM card for around $30 will give you full functionality for a month. Several people on the Ireland trip did this and they were very happy.
3. Your carrier will have temporary plans that you can sign up for that will give you full functionality but this method is probably the most expensive way to go.