Hi, I am from England as well - Spectrum - possible but as I had to pick one of the other , C64 or Spectrum to start with, and I had a C64 and graphics were more colourful and sound was much better.
Master system - not sure as, may add a misc section but most games were available on the other system, Mega Drive for example. I tried to pick the best version of the game and covered that.
May happen but not for a long time. MSX and Dreamcast are currently being worked on.