If you are serious and want a well bred, health tested, well socialised pup who has been reared with care then you will find that you may have to wait, good breeders don't have litters available to order - only puppy farms have the numbers of dogs to ensure ready availability, but the pups are often unhealthy and unsocialised and the cost in heartbreak can be very high.
Cavalier and Cocker clubs can be found here under the relevant Breed Standards and the club secretaries should be able to help
http://www.the-kennel-club.org.uk/