No I'm not suicidal(at least not before this morning)
Cleaned the oven - nearly finished.
Used a hot oven spray followed by degreaser spray followed by brillo pads followed by a screwdriver.
Screwdriver firstly was to remove the inner door from the oven (nightmare to get the seal back on) then in desparation to get the big lumps of grime off.
Can understand why there are companies to do this for you!