I've heard good things about the Pottergate centre:
http://www.dissociation.co.uk/
I think it's super-pricey and probably not near where you are, but they have a page with advice for finding a therapist and they may be able to give you some advise on finding a therapist in your area via email if you ask?
Could you ask the worker who suggested that you have elements of DID what dissociation-specific support is available within your local NHS mental health care?