Single built in fan assisted oven - full working order (Stanley DH9)

I have an IKEA single fan assisted built in oven if anyone can use it. There is a snag though - I started to clean it with Astonish paste but due to health problems I couldn’t get it finished. So it is in need of a good clean but I have a box of oven cleaner that can come with it. It is in full working order otherwise, so it’d be a shame to scrap it. I had wanted to upgrade it (to one with more shelves), so just decided to do it now. It kills me to have to offer something which needs cleaning, but hopefully someone won’t mind doing it and will save it from scrap.