If you have broadband Internet to your house, a WiFi router will allow you to share the connection with multiple devices without running Ethernet wires. It also means that your laptop can be moved about the house without loosing the connection and without a cable.
I don't know what the situation is like in the UK. In the US, many hotels now offer free WiFi access to the Internet for guests and some Airports have free WiFi. Most WiFi hotspots, though, require payment. Either a daily sign-up or a monthly subscription. Two examples are McDonalds and Starbucks.