Agree with UKA, you need to speak with your vet first. In addition, any Physio, Osteo, bodyworker etc, all need your vets permission before they work on your horse.
Before any therapist can work on your horse they need to obtain (or you to obtain on their behalf) permission from your vet.
Whoever you use ensure that they are qualified, registered and insured. You can find this out by checking the member body of the therapy that they are practicing.
In your situation I'd more than likely get an Equine Body Worker (list in your area can be found on equinenergy website) as foot problems can, as you know, cause problems from compensating throughout the body.
Although you'll probably get as many replies saying physio, osteo, McT-C etc. It's all personal preference based on the individual's experiences. Word of mouth is probably your best way to get a recommendation.