Updated: May 17, 2020
In the UK they use power sockets & plugs of type G.
The standard voltage is 230V, and the Frequency is 50 Hz.
It is highly recommended to purchase a plug adapter in advance:
If you live in a country who uses different voltage (like US, Canada. Australia and some countries in Asia and Africa), you must check the labels of your appliances, to see if you can use them. If the label states: 100-240V, 50/60 Hz, then the device can be utilized worldwide. If not - you need a voltage converter. You can also purchase a compact converter & adapter combo like this:
If you want to recharge more than one device, you should probably take a power strip: