You will really love Cairo. I hope your move goes well. I have been living here for two years (originally from London) but the other side of Cairo where you will be and I love it here. Maadi is a really nice area - find out from your school if they will get a school bus to pick you up in the morning - because traffic can be terrible. Also check out new Cairo and Kattameya and Zamelek or Helipolis (Masr Gaddida). Have someone from school help you with your flat hunting and really make sure you get rid or or ask for any furniture you want removed because once you move in its hard to get rid of stuff. Make an list of everything in the flat and ask for the locks to be changed as landlords can let themselve in. They are very attached to their flats.
If you havent been to Cairo before - there is everything you need. City Stars is a massive Shopping Centre and Maadi has Carreforre supermarket. If you need anyhelp let me know. No trouble.