If you know a jockey then have them come help clean the inside of the oven !! the door is @35cm sq thus @ 50cm diagonal and my shoulders are 54cm across, I have to jimmy up the ladder backwardsslide my arm in with 1 shoulder then pull my other arm in. Sounds easy !!! but I stretched a muscle and got a cramp whilst inside, i couldn't get out and thankfully it subsided but it wasn't pleasent.
The other thing is I have cleaned the inside as I have gone, not leaving it to the last minute so this last clean shown was only the drop and side bricks. Keep cleaning them bricks whilst the front area is open.
I suggest you "blind clean" the inside front, meaning just stick your arm in and scrub, then go inside and do the bits you can see, I ran a small table light into the oven so i could actually see.
All i used was a scourer and water and then a cloth to wipe the muck off. it really only took me 10 minutes to finish it off.