We are currently seeing a well respected holistic vet who is a homeopath. I am very impressed with her.
The thing with homeopathy is that the remedies must be tailored for the individual dog. A homeopath treats the individual as a whole.
A consultation with an holistic vet is very different from one with a conventional vet. So while there are various remedies which are used regularly for particular ailments, and can be bought online, there is nothing to say that what helps one dog will work for another. Some homeopathic remedies can be potent and ought to be prescribed and used under the direction of a professional. It is well to remember that some of these remedies can actually cause an exacerbation of an existing problem at first before it goes on to help.
If you decide to go down the holistic line I would recommend that you consult a member of the British Association of Holistic Nutrition and Medicine