>This is not a decision I would take lightly and as a fairly new dog owner I was hoping for some advice on factors I should consider before moving forward with this.
I don't want to cause offence, but as a 'fairly new dog owner', I'd suggest it's best not to be planning on breeding. Any bitch owner coming to you expects not only that your dog can do the deed which is worth their money, but also that you can achieve the mating, assist and ensure the dog is able to mount, understand when a bitch is protesting but doesn't really mean it versus a bitch which really isn't ready and should not be mated... and so on. As a 'fairly new dog owner' you are unlikely to have acquired the experience needed to be able to provide someone who is paying you, with all that.
>For example, does breeding change the temperament of a male dog.
Sometimes. Sometimes a dog may become reactive towards other entire males, perceiving them as threats. Sometimes a dog may become less reactive because they feel more secure in their identity. Sometimes a dog may become more distracted or ignore recalls if they can smell a bitch in heat. Sometimes they get better at knowing where a bitch is in her cycle and are not distracted during the rest of it. And so on. The fact is that every dog is an individual and will be affected differently and it's not really possible to predict.
>What health checks etc should we have carried out on our dog before offering him as stud, what checks should we expect a potential mate to have carried out and so on.
This is a breed specific question, because the health tests which are required for each breed, differ. Contact your breed club for advice. Look at puppy adverts from reputable breeders (some of which may advertise on CDs but not all breeders who advertise on CDs are reputable, so be warned) and see what tests they do.
>I feel our dog is a bit young to be bred at the moment....what age is acceptable?
Yes 1yo is far too young, he is not even out of adolescence yet and you don't even know what his adult temperament, personality, health tests and potential are. 2yo should be the minimum.
>And where locally can we get some advice/support on the matter if we do decide to move forward? We are in Northern Ireland.
I'm not sure what advice or support you're looking for, but if your own breeder can't provide it, there aren't any sources of it other than some excellent books and online resources. Certainly nothing locally to anyone.
You haven't really said WHY you want to breed your dog? Unlike the owner of the bitch, you are not going to whelp and raise puppies (which for some reason is what appeals to people most). Someone is going to bring a bitch to your house for 'service' twice - and they pay you a not-very-huge fee - and that's it. Frankly, unless you are really into showing or breeding towards a particular goal, I just can't really see why you'd want to do it. They may or may not allow you to buy one of the puppies, that would be a separate arrangement. And the cost of doing all the health testing is probably going to be more than one stud fee anyway.