Do you mean it's not a character in the Symbol font set - if so, that's correct. It is a character in most regular fonts though.
If you've got a UK keyboard, and your system is set for a UK keyboard, then it's on the keyboard anyway. If the pound key does not produce a pound character, then your keyboard is not set correctly - which OS are you using?
"Hi .Thanks for your message. Yes its the pound sign thats with the figure 3,on the keyboard, but I keep getting the hash sign instead. Am using Win ME. My ALT is also in the wrong place too, its with the figure 2. Cheers Al."
You need to set your system up for a UK layout keyboard. What OS are you using?