Are you in the UK? (You said 'trusts'). If so, then I think it's all regulated by NICE. They will assess the clinical evidence for the intervention, and then recommend whether/who it should be offered...
Not all training in the UK is three years, I am currently doing my training, and it's a two year post-graduate course. There's only a couple of these courses in the UK, and they are not well known. We...