Should i use my dogs breeder as a mentor when thinking about breeding and showing? Is it possible to seek advice from other breeders?

Yes of course ! The more help and advice from experienced breeders the better ! :)

I know of many breeders of my breed, but can anyone recomend an 'approachable' breeder. (Staffordshire Bull Terrier)

Not quite sure what an 'approachable' breeder means :)  I believe it is always best to source a breeder through the breed club as they will put you in touch with breeders that conform to their code of ethics which is the best way of finding a breeder of healthy puppies and offering a high standard of support both in helping you decide if the breed is appropriate for you and your circumstances and dealing with any problems you may experience in the future if you do get a puppy from them.  Not sure what other values 'approachable' might bring you but perhaps the club will be able to help you with that also :)

Yes, I agree with Isabel, the breed club are the best people to give a ring or drop an e-mail to. Have you thought of the breeders on Champdogs too?

My best mentors were my mother and my girls breeder, through my breeder I got to know lots of other breeders maybe this is a way for you too, she happily took me along to see stud dogs and other breeders in action, you can also meet people at shows or field trials you may just click with someone.

I always introduce any of my pups owners who become interested in producing a champ or breeding to everyone I can think of, an overload of knowledge is always better than none at all, and all good breeders need to know where the good stock is. ;-)

But you need to put yourself out there.

I always find that when people are seen regularly at shows, showing interest, trying to learn, then there isn't a shortage of people who are happy to help. 

The ones who get short shrift are the people who sit at home and expect breeders who've put the time, effort and money in for many years, to pass on their knowledge. Or even worse, ring a breeder that they don't know and say "I want a bitch puppy to breed" :(

Most breeders are only too happy to give help and advice. All breeds need a constant supply of new enthusiasts and any breeder worth their salt will recognise this. Try to choose somebody who lives at least within a couple of hours drive. Somebody who breeds and shows the type of dog you like and above all, choose somebody who is willing to sell good dogs to other exhibitors. It shows a generosity of spirit.