
Hi! I'm assuming she's Kennel Club registered, and generally the best person to ask for advice is the bitch's breeder who, if reputable, will be able to tell you which would be a suitable dog and which bloodlines to avoid like the plague! Luck being what it is, you'll probably find the most suitable stud is well over 100 miles away!
Your bitch will also need to have a good hipscore (breed average is 14 I believe) and a current clear-eye certificate - as will the stud dog, of course. Three years is the right age for a first litter, so that's all right.