I have just had the same problem with my/B cooker. I don't know what model mine is but I will share what I know with you. Mine has a glass cover over the bulb on the left side (as you look in the door). It's rectangluar in shape. All I did was get a small (ish) flat blade screwdriver and gently prise this off. First from the front and then from the back until it came off. It is similar to taking of an car interior lamp cover. When it was off it was just a case of unscrewing the bulb & replacing. Mine was a 25W edison screw thread. Don't know if all this sounds like your oven, so all I can do is hope it helps in some way
K.D
December 2007