There isn't really a guitar riff on this track, but this is how to play along with the
or whatever its meant to be.
[ Tab from: http://www.guitaretab.com/d/dizzee-rascal/90647.html ]
e|---------8--------8-----------8--5--3--2-----------------------------------|
B|---------8--------8-----------8--5--3--2-----------------------------------|
G|------------------5--------5-----------------------------------------------|
D|-5-5-78---5-5-78---8-757-----8--7--5--4------------------------------------|
A|--5--------5---------------------------------------------------------------|
E|---------------------------------------------------------------------------|
There's odd little variations throughout the song, but you'll be able to hear them and
them out as you listen to the song. The notes and order never change, but there are
gaps etc.
Don't try to play along to the synth part though, its a different key or something.