Try this link Miss:
http://www.equine-world.co.uk/information.htm
It seems to be quite a useful website.
I expect New Forester is the man to ask and I am sure he will be along shortly.
I believe someone who specialises in horses is called an Equestrian Specialist
Sir Fakeplastic? Miss, I'm Madam Fakeplastic!
If you go into that Website you will find a section on working with horses. I expect the qualifications will depend on what you want to do. Very different qualifications required to be an equine vet to becoming a groom or stable hand.
Lets see if New Forester has any ideas.