International political exploits, real and imaginary, will provide a theme for The Washington Post's spring Book and Author Luncheon at the Sheraton Washington Hotel tomorrow. The featured speakers are Sens. Gary Hart (D-Colo.) and William S. Cohen (R-Maine), Tom Clancy, Gary Sick and George Stevens Jr.

Hart and Cohen wrote the new spy thriller, "The Double Man," the first novel to come out of the Senate. They are members of the Senate Intelligence Committee.

"The Hunt for Red October" has been a surprise success for Clancy, a first novelist, and the book's publisher, the Annapolis-based Naval Institute Press. This tale of a Soviet naval commander's defection to the West found a fan in President Reagan, who called it "non-put-downable."

Sick, a former special adviser on Iran to President Carter, will discuss the events chronicled in his book, "All Fall Down: America's Tragic Encounter with Iran."

"Victory in Europe," by Max Hastings, author, and George Stevens, photographer, commemorates the 40th anniversary of V-E Day. George Stevens Jr., who wrote the introduction to the book, will represent Hastings and his late father at the luncheon.

Leonard Downie, managing editor of The Post, will preside at the 12:30 p.m. luncheon. Tickets are $13, and reservations may be made by calling 334-7969.