try this link There is no mention on the site of the various health checks like eye certs that can only be done by specialist vets not "GP"vets. They may be licenced but that is not necessarily a recommendation
Before buying a cavalier the parents should be heart & eye tested(they should have been tested not more than a year before the date you see the puppies-tests older than this are not current eye & heart certs are a yearly test & there is no test for Syringomyelia)& both parents should be over 2 1/2 years of age & not have line breeding on both sides of the pedigree & of the breeder has not heard of syringomyelia do not buy