I've done all now, the bulbs that shine down R.E. map lights were easy, theres 2 like vent things on the unit, on the side furthest away from the windscreen get in a small screwdriver and that just pops of, under there is 2 x Torx screws 9will get size in a minute) undo these and the unit is free to come down.
To replace the bulbs there in sexy little holders, just twist the holders anti-clockwise, bulb out the bulb and replace. I had to turn my LED bulb around once of twice to get it to work, but I swapped them whilst the lights were on so I didn't put everything back and it not to work. This might be un-safe I'm not sure!
Hope this helps!