CAA Display Authority
For Bellringer .... Not mentioned yet, but your first port of call should be the Display Pilot's 'Bible' ... CAP 403 Edition Thirteen 2. (13th April 2016.) You can download the latest copy from the CAA's web site.
Then approach any of the Display Authority Evaluators (DAEs) mentioned above. They will guide you and can arrange to 'Mentor' you through the process. I take the view you need something in the region of 500 type hours and undertake a period of specific display training. The rotary wing side of our display industry does need a few more active display pilots.
You'll be welcome to the club. Fly safe. Dennis Kenyon.