have pedigree black labrador - 2 in May. Would like him to sire litter but not sure how to go about contacting suitable bitch.

Live in Staffordshire - suggestions please.

You don't...owners of suitable bitches contact you!
So the first step is to have his health tests completed which will cost you several hundreds pounds(hips,elbows and eyes I believe?) and then get him either working or shown to get him seen by bitch owners
I would also suggest you read the first post on the breeding board first to see exactly what you are letting yourself in for
Archer