William J. Bennett, a magnet for controversy throughout his 31/2 years as secretary of education, is getting ready to take an early fall departure from the Cabinet.

Bennett told education writers in New Orleans last month that he probably would resign then. His spokesman, Loye Miller, denied rumors of a more imminent departure.What lies ahead for the brash, combative Bennett, who has clashed repeatedly with teacher unions, quarreled with the surgeon general over AIDS education, accused college presidents of being greedy and upbraided Harvard and Stanford for changes in their curriculum?

Bennett and his aides were not available for comment this weekend, but he is expected to hit the lecture circuit and to write a book capsulizing his critiques of the quality of America's schools and colleges.

Bennett, who converted from the Democratic to the Republican party on May Day 1986, has already proven a big draw on the GOP fund-raising circuit, where he has been much in demand as an after-dinner speaker.

One speculated post is apparently not in the cards: the vice presidency on George Bush's ticket.

Although Bennett is widely believed to have had his eye on that spot, Bush has been conspicuously silent about Bennett during all his talk about being "the education president." Aids to Bennett, who asked not to be identified, said they have had virtually no contacts with the Bush camp in recent months, and Bennett is not expecting to play any formal role in the Bush campaign.