If you've ever wondered what Estelle says right before Kanye West's rap, like I have, you'll be pleased to know I think I've found it.

According to the Internet, it is “wagwan blud”.

Now to me, who isn't very street, and most of the population, who I am also assuming aren't very street, this doesn't make much sense. However Urban Dictionary steps into the breech to help us out.

wagwan is apparently short for “What's going on?”
blud is short for (in this context) mate.

So, in summary, what she is actually saying to Kanye West is “What's going on mate?” Makes perfect sense now!