Hi tris54,
Sorry for the late reply. I just saw your e-mail. I live in Cairo, Egypt, so most obviously, I am the most perfect person that I can reply you !!!
You seem to be nearly my level. I just passed my grade 8 last month and me too I wish to continue to diploma. The problem in Egypt is that classical music is not an appreciated art at all

People think of it as being so sophisticated and only the elite listens to it. There are so few people in classical music concerts (although we have a brilliant orchestra, Cairo Symphony Orchestra).
We have some outstanding performers here, but not many. Most of them are conservatory graduates. We have some young emerging talents, besides the old guys such as the all-time best Egyptian pianist, Ramzi Yassa, who is now in the faculty of the Ecole Normale de Musique in Paris.
About learning piano, there is not much good places, but you can always search for conservatory teachers. I can guide you to some good ones, such as the one I am studying with. I am not sure about the diploma though. ABRSM is not much of a public thing as in the UK. Only very few musicians know what's ABRSM and of course you don't wanna go study for DipABRSM with a teacher who doesn't know what's a diploma !! I did that for my grade 8. I only studied the pieces with my teacher, coz that's what she can help me most in.
I am not only a piano enthusiast. I feel i am drowning in music !!! It will be great to get in touch with you if you come here. I have so few people to talk about music with. Just tell me when you come, I can be your tour guide here !!!!
PM me and I'll be glad to keep in touch.
Cheers and Welcome to the Land of the Pharaoes !!!