Speaking as a DA Evaluator myself, what tends to happen is that you call the CAA Displays chap, Matthew Hill on 01293 573510 and tell him what you want to do. He will then give you the name of a suitable DA Evaluator in your area. He'll probably also want to know about your flying background and almost certainly ask for your flying 'CV' before he'll send you an application form with a provisional DA number on. He's the only one who can issue this form, and without this, you can't go to a DAE for an evaluation.
There are a couple of DAEs in the South West, but without knowing what type you want to do it on, I cant really help any further.
A list of Display Authorisation Evaluators is available from the CAA FOI(GA) Department.
The CAA haven't issued 'a list' of DAEs for years.