Sorry, this is a long, rambling attack of nerves!
I finally 'bit the bullet' and made contact with the local gifted children's group. I saw they had some activities my LO would really enjoy coming up! They usually require a parent form and a teacher/childcare worker etc nomination. But because my LO is home educated, and has never been in care, that's kind of a problem!
I wouldn't sweat this. He's four, why wouldn't he be "home educated"? Not trying to put down your efforts, just attempting to give a little outsider perspective. If their criteria is preschool teacher/childcare worker/babysitter recommendation then they are really not all that serious about identification.
I guessing that either they take every child whose parents bother to go through the process (which is is probably a reasonably effective screen) or they are a clique and they are going to be more concerned about YOU than your child.