If the bulb had come out easily, then the right-hand bulb could definitely have been changed by only going in through the drivers footwell, but there is no way I could have got in there to yank it out with the force it actually needed. You may be able to do the left-hand bulb that way, but as I couldn't even see the wires leading to it, I didn't know where to put my hand. Now I know where it is, next time, I might try it all through the footwell. TBH removing the stereo was not particularly difficult, other than the cage on mine fits by bending pieces of it outwards to lock it in place. You have a lot more room to work with the stereo out, as with a little jiggling even the BMW to ISO adaptor with come out through the cage.
I did not fully detach the heater controls, as the bowden cables look an absolute pig to remove. However with the fan switch connector removed, the controls would rotate so that the dials were facing downwards and the opposite way round to how they normally sit (i.e. direction control nearest you) and could be poked partially through into the footwell with the bowden cables still attached. This meant I could get to the bulb easily and get the pliers on it with enough force to pull it out. I seriously thought it had been superglued in, it took so much force to get it out! There is no way the controls can come out through the stereo aperture, as they are quite deep. Having said that, I didn't actually try after I removed the fan switch connector.