>surely a 8 week puppy can't be agressive??
No, you're right, he can't! This is normal for puppies, just as it's normal for children to shout and scream when
they're playing. As for the 'nipping' this too is normal.
This article should help you get that sorted out.
I'm very concerned, however, about his eye problem. Reputable cocker spaniel breeders are working hard to eradicate the eye problems in the breed and screen all their breeding stock every year to try to save owners the heartbreak of their loved pet going blind in its early years. Unfortunately there are also the not so conscientious breeders who don't bother. :( These eye conditions are progressive - if your pup is having vision problems at a few weeks of age the prognosis isn't good I'm afraid.