I didn't think it looked fat - fluffy and fuzzy more than anything.
But I have a question about it's ears. Do they always stand up? I mean, from birth? I ask because I've had 2 boxers - and with boxers you have to go have a vet crop them to make them stand (and less and less people are doing that to their boxers now btw, I guess floppy is 'in' for them) - and then I have my German Shepherd, who had floppy ears until she was a few months old and they gradually stood up on their own. Corgies are born with the upright ears?