Where/Who do I go to in order to enter for participation in my first Air Show in the UK?
I’m sure this isn’t an easy thing to do but my initial searches haven’t been much help…
The first place I'd start is British Aerobatics who are located at a lovely little airfield called Fowlmere just to the west of historic Duxford. They're a really helpful bunch, I have flown with them a couple of times. I'm sure they will be able to put you in touch with the right people to get involved in airshows.
They also have a a page on Entering competitions which you might find useful.