Hi Gareth.
No you won't see objects as they appear on telescope boxes or in here. But as Rob says, you eventually train your eye to see more and more detail each time.
Below I have used an image of mine, and also I placed that image into a rendition of what it actually looks like thru my 12" dob at my very dark sky site.
It gives you an example of what you can see in good dark skies with a 12".
Obviously it will vary from scope to scope and seeing/light pollution, quality of EP's etc. But this is how I see it.
Below I use Trifid as the example, but thru 12" and larger scopes some colour can be seen in Orion nebula.
Planets show nice colour, but DSO's are 99.9% grey.