If the housebuilder refuses to fix these then yes you will need to get estimates and take them to Small Claims Court for the cost.
It all seems quite small beer. The internet socket should be easy to fix if they send someone that knows what they are doing.
Scratched floor, take up and replace days work plus materials.
Knocking pipework, small hole, wrap pipe in insulation at knocking point and make good and decorate.
Regarding his attitude, I suggest you get a solicitor to send the housebuilder's his solicitor a full list and give them 28 calendar days to fully rectify.
Stating if they refuse of fail, then you will appoint "A Another" to carry out all the required works at their cost plus 10% management and inconvenience fee plus your legal and court fees and all other expenses. plus 5% interest on the total until it is paid. You could point out that it is a public court and you would also ensure local and if a major builder national press are present.
Time to get tough!
The house builder will end up spending more on legal fees than it would cost them to do the work.
Warning to others this home has a Checkmate warranty....beware!