First of all who is your housebuilder?
Others need to know this is what they can expect if they also buy a new home from them.
Regarding the kitchen, you didn't damage the worktop. Your kitchen is new and should not be handed over to you damaged. The problem is fully the making of the housebuilder.
You need to tell them that either they swap the damaged worktop in the showhouse with yours, which is what most site managers would do, OR they agree to give you the upgraded kitchen doors.
I suggest you instruct your solicitor (hopefully not recommended by the builder) to write to the builder and state that you will not legally complete until this is resolved.
Be aware that worktops can be repaired by specialist firms like Bath Doctor and Plastic Surgeon. You may discover the damage has just been camouflaged with filler and paint - which will wear off in time.