Guest,
I'd suggest that you join the Labrador Retriever Club :
http://www.thelabradorretrieverclub.co.uk/The yearbook contain contacts for most of the UKs top show kennels. If you dont know anyone who can propose & second you for membership, then I'd suggest visiting a few championship shows and having a chat with some of the exhibitors. You should be able to meet most of the top breeders there and then, and perhaps seek out someone showing labs of a type that appeal to you.
I'm sure that the top kennels will assist and encourage you in starting to show your bitch. Given the huge amount of labradors that are bred, they will probably try to dissuade you from breeding a litter until you have a really exceptional bitch in your hands.
If you are looking at breeding labradors for showing, I'd strongly advise you to attend some working tests / field trials to get an idea of the working requirements of the breed. Even if you have no interest in working your dogs it will give you a good grounding in the function of the breed and hopefully give you a balanced perspective on the 'type' of labs that you are striving to breed.