What do i need if im a us citizen going to england?

You don't need a visa if you stay for six months or less. You just need a passport.

Your credit card should work in UK. However, it's advisable to let them know, so they don't think you are making "unusual purchases"!

Bring layers of clothes. It's not as cold or as wet as you may think but the weather is very unpredictable.

If you find you have forgotten anything. Don't worry. Everything is available here.

Have a good time!

Get a prepay visa/mastercard and you can use it like any credit card for purchases and cash - no bank charges to pay and you don't have to tell them that you are travelling abroad - you can't use it as a deposit for hotels or car hire though. Summer is cooler and winter is milder than the northern half of the USA and humidity doesn't exist on the same scale

A visa, and plug adapters for your electrical supplies, and voltage converters for anything that isn't dual voltage.

Clothes that are appropriate (it will be anywhere from cooler to a bunch colder, depending on where you are from, than what you are used to).

There is very little that you will not be able to buy, so try to travel fairly light.