Hi,
The most recent dog I registered on the activity register was my Mum's CKCS on the activity register a couple of years ago. The form has changed a little I think (e.g. I dont recall naming an activity for her), but is mostly the same.
She's a rehome and I don't know who bred her. If I remember rightly I just filled in everything I was able to (a choice of names, breed, colour and sex). Everything else is left blank as it's an unknown. I used Form 5:
http://www.thekennelclub.org.uk/download/378/form5.pdf There are some guidelines attached to it which explain in more detail how to fill out the form.
If you do know the breeder and can get them (and the stud dog owner if not the same person) to sign the registration papers it means you can register her D. O. B., parentage, etc. The form you would need would depend on whether her sire and dam are on the breed register or not.