A collar and tag for your dog is a legal requirement
The main thing to think about when buying a collar for your dog is to get one which will grow with them. You should be able to comfortably insert two fingers behind the collar, or it is too tight.
In the UK a tag must have the owner's surname, address and a contact number on it. The dog name is optional. We don't put our dogs' names on their tags, just to prevent anyone malicious knowing their name.
By law the dog should also be microchipped - your breeder should do this for you, or their first vets appointment. You will need to register your details along with the dog's ship number with a database centre when you bring him home.