Share 'Soft crate size?'

Could someone advise what is the best size/make of soft crate to get? I have two setters and a Ford Focus estate with a dog guard which is fine on short journeys, it would just be mainly for showing the pup, who will be full-size before I know it! What size do most people use? Are big crates a problem at benched shows? I'm looking for a UK supplier? Linda xx