I have had a oil smell in the engine bay which you can smell inside the car for a while now so decided to take a look I removed the air box and was greater with this it seems like the foam protector on top has melted also the air filter has oil on it do you recon a good clean up would sort this out or is it something more

A good clean would help for sure ...it that melted plastic or burnt oil on the head and where is it coming from. What is the air box like inside ? .. Btw What car what Engine... 16 valve?

Injector seals Allmost certainly looking at the build up around them
With the black sludge I'm guessing this is a diesel?
Edit to spark plugs and direct injection so 100% diesel