Despite its fan-magazine quality--H.R.H. is ""embarrassed about his jug ears and weak chin,"" etc.--we learn as much from this account of Prince Charles' first 30 years as almost anyone could want to know. Inescapably, it is largely a chronicle of schooldays--Hill House, Cheam, Gordonstoun (his arrival was ""even more miserable than at Cheam""), Geelong in Australia, and Cambridge. Holden--now U.S. correspondent for The Observer--does take us into Buckingham Palace, where Charles often dines alone in his baroque sitting room with TV his ""only evening companion."" We learn that he was closer to Prince Philip as a child; that ""his mother is the mainstay of his life""; that he depended on the Queen Mother during his homesick school years; that he has a ""combustible"" relationship with Princess Anne. Despite his sense of humor, ""he expects the deference due to his office,"" and ""will not gladly suffer any undue familiarity."" He falls in love easily--Britain is agog over his choice of wife--and probably will marry in his thirties because of ""his duty to breed heirs."" He loves flying, learned Welsh to placate his independence-minded subjects, and may become Governor General of Australia before taking the throne (Britain is also agog over when Queen Elizabeth will abdicate), As the Crown's roving ambassador, Charles must keep his comments ""wholly innocuous"" (his college desire to join the Labour Club was quickly squelched)--and by comparison with his colorful predecessors, he is among Britain's more somber Princes of Wales. Like his role, more ceremony than substance.