Here's a keyboard shortcut that you could use: Alt+0163. Hold the Alt key as you type in 0163. It works for me... £. If you don't want to memorize this shortcut, there are keyboards that include a £ key. That is more convenient.
You can use the "insert symbol" from Word. Of course you would have to be typing in Word do this. Then you can cut and paste it into whatever you wanted to put it in.