Ring them. The breeders I know don’t bother to reply to emails as they get so many. A telephone call is faster and more effective.
remember for breeders a lot of people flake, vanish after several conversation of how much they want a puppy from them. Or ring and say they want a puppy but are ringing lots of breeders in succession and will never call back the other five (or however many you ring) once they’ve found someone who’s having a litter at the right time with the right sex they want so you should ask them (if they’re having a litter around the right time) if they want you to ring back even if you’ve found what you need elsewhere. They may say no don’t worry about it, but it’s good manners and things fall through all the time, and you may want another dog in a few years so trying to have a sort of professional courtesy is helpful to everyone if a little more work for you.
Also, obviously having a litter is in the lap of the gods so to speak - a breeder may hope to have a litter or 2 in the spring but who knows if it will work. Or how big, what sexes and they may want to keep one themselves.
word of mouth recommendation is good - but going to meet a breeder at their house is the best way to check they’re not a puppy farm. You can see how many litters a bitch has had on the Kennel Club website if registered and it shouldn’t be many, they shouldn’t let you see puppies before they’re 5 or 6 weeks old really as it can distress the mother.
Ideally you should be asked lots of questions like how much are you out of the house, are you planning to insure the puppy, what’s your experience of dogs, do you have children do you have a garden or outside space, any worries about owning a dog etc. there is no right or wrong answer to these but the breeder should be interested to know what sort of home their puppies are going to and also be happy to answer questions you might have.
There may be a breed club which has tips on personality and shows and how to groom on their website and they often have a list of breeders who are worth getting in touch with. But it’s not fail safe. I’ve met breeders who have a council licence, registered with the KC and on the list of the breed club and I wouldn’t get a puppy from them.