Take your ATM card and draw local money when there. There are plenty of ATMs. If you are worrying about tipping on arrival, a pound coin is a very generous tip for anyone.
If you want to take Sterling in cash, you will have no problem (2 branches of HSBC in Sharm, and many other banks) changing it there also. You will get MUCH better rates changing Sterling in Egypt than in in the UK (20%?)
Don't change your UK money to $, just to change to Egyptian (EL) for some supposed advantage, there is absolutely no point. Egyptians will take any money, trust me :-D
But the ATM card is the best way, plus a Sterling cash buffer that you keep in your room-safe 'just in case'.
[Been to Sharm 10+ times, so I hope I know what I'm on about]