Can someone explain BB/CC creams to a novice?

[MyGastIsFlabbered]

What are they, what's the difference, and should I be expecting to see DD creams any time soon?

Dd creams are already out there! As far as I'm concerned it's all marketing and they're all essentially tinted moisturisers/light foundations (the Western ones anyway, BB creams from Asia ime tend to be thicker and somewhat more opaque - I haven't tried any for some years though so this judgement may be out of date!). If you ignore the letters on anything you can buy in Boots and just think of them as tinted moisturisers you won't go far wrong.