You may well not be able to get Egyptian pounds before you travel, and just fyi - there's a strict low limit on the amount you can take home, about �50 sterling.
When i went there the advice from Lonely Planet proved invaluable. Buy travel cheques - if you get US dollars now you get a good rate - and change in the bank there. Almost every hotel above 3 stars has a bank in the lobby. Also, the people there will happily take euros, sterling and dollars, but be very aware of the exchange rate as prices will be in Egyptian pounds.
Last things - if you're buying - haggle like crazy, it's expected. Also, hoard small Egyptian notes to use as tips - again, very much expected (look up Baksheesh - you will get to know this word very intimately).
More tips here
http://www.egyptsites.co.uk/travel/money.html
http://www.lonelyplanet.com/worldguide/egypt/m oney-and-costs