I wouldn't worry too much about the six month interval if it is running on the same oil, but watch the dealer like a hawk. They have canny ways of scamming money out of us with ridiculous extras that we don't always need.
12 month warranty, but according to the recently reset service indicator that will take me nicely back to my trusted mobile MB mechanic.
He mentioned the fact that the car had been given paint protection for free. Again, don't believe it but will ask for the relevant paperwork.
The only thing I did go for was alloy wheel insurance. Three year cover comes in at about £280, and that included up to 18 repairs. They will get damaged, so I didn't reckon that was a bad price.