right then here are a few quick pics i've just taken, excuse the dirty car :lol:
start off with putting a small flat balde screw driver either side at the bottom and work your way up slowly prising forward the surround
as you can see the surround has moved forward
then you will see 2 screws (black ones), one either side of the headunit, remove them.
And then with a little bit of moving around the whole unit will move forward but not the heater controls that part is seperate.
when it comes to refitting the surround there is 4 metal clips which need to be positioned correctly otherwise it wont go back on properly
hope that helps mate.