Its a fiddly job to do, but well doable yourself. H8 bulb, think osram are the OEM for the E90. There is a flap on top of the headlight assembly that you can open to gain access.
The M has the same front as the coupe but I think you can get to it from the top/behind rather then from below.
E90 M3 S65 4.0, Silverstone II, Black Novillo, 19\" double spoke, EDC