MikeHotel152:
As you are a relatively newcomer to the wonderful world of light aviation, I can assure you that there are many people and associations that represent your interests, as others have indicated, and they are very active. And they work closely together for the most part, particularly so in recent years with the increased threat of advancing regulation from within the UK and from Europe.
It would take a long time to provide a brief on all the activities that meet your list. There is no single association that covers all aspects of GA - partly because of history, but also because of the specialisms inherent within a broad based community called 'GA'. However, although we do not speak with a single voice, as some in government would wish (for their own convenience I suspect - fewer meetings), we do on the whole speak with a co-ordinated voice. And the common goal is the freedom to fly, how and wherever we want, within reason bearing in mind consideration for others and related safety aspects.