First of all, go to the AR dealer and buy 6 new instrument bulbs. They're a bit dearer than Halfords etc. but the type Halfords sell don't quite fit right. If you compare a Big H (Bosch or own brand) with the AR type, you'll see the difference. Anyway, the difference is £3 vs £2.. so not the end of the world.
Undo the allen bolts on the inside of the instrument pod. That lets the inner moulding come out.. but it's difficult to remove. It's held in at the bottom by 2 arrowhead clips so the best technique is to push the moulding inwards, lift it at the bottom (the clips are about 4 or 5cm in) and then pull it out.
That frees up the instrument pod itself. You can pull it out about 4 or 5" before you run out of slack in the cables... but that's enough to disconnect the cables.
I can't remember if there's another cover on the back, protecting the bulbs but it's a few screws I think.
The bulbs come out by twisting them 90-degrees anti-clockwise then they should come out.
Change ALL the bulbs so you don't ever have to change any of them ever again (seeing as they last for years).
Don't use LED as that's better for spot lighting.. you want a nice diffuse light, so use the regular bulbs.