oven cleaning

Hi everyone, I was thinking of offering oven cleaning as a side service in the new year after seeing quite a big demand for it locally. I've actually never cleaned an oven before.. (the wife does it) and wondered if anyone on here already does this and could offer any advice or guidance on the...

today I had an idea - why shall I spend hours manually scrubbing the oven if there is a much quicker way to do that - no chemicals at all and the "kit" costs under £20 haha the other side of the tray was horrible - it could ve taken me few hours to clean it the way...