does the cable need to go into broadband socket for full fibre? is that still needed?
With Full Fibre you've got the ONT box which is connected to Port 4 on your SmartHub2 and that's it.
The cable you're referring to is presumably the old cable from the phone master socket which will still service your phone line unless you've got Digital Voice.
On the back of hub next to phone socket is marked broadband... so i dont beed thar now? Some reason its not connecting and its runnimg off hybrid connection
You don't need that connection.
Make sure the hub is configured for full fibre mode and the ONT is connected to LAN port 4 on the hub.