You can probably get in touch with him through his publishers' website, Simon and Schuster. See the related link below.
By giving a bit more information. Which one are you looking for?
David Icke was born on April 29, 1952.
Extremely doubtful, IMHO. In real life, no one could be that far off the beam. He earns a living from writing and public speaking. I can't see into his mind but it may be he is a contrarian...
Write to his fanmail address. You can find the address on david-tennant.com