Lech Walesa plans to call on Poles to use all possible peaceful methods to defend the ideals of his outlawed Solidarity movement in a speech Thursday marking the 12th anniversary of the bloody suppression of food riots along the Baltic Coast.

An advance text of the speech, made available to foreign correspondents here today, provides the first real indication of Walesa's hopes for the future since his release from internment. It amounts to a continuation of the struggle for various kinds of independent social organizations but a jettisoning of the ambitious political program that Solidarity set for itself prior to last year's military crackdown.

In the prepared speech, Walesa attempts to reassure Solidarity supporters that he remains committed to the cause of greater freedom and democracy in Poland while attempting to persuade the Communist government that he does not pose a major threat to its political control. He promises workers that, despite present disappointments, "victory will be ours" but promises at the same time to work toward true national agreement.

"Our cause is not aimed against anybody. We don't want to overthrow the authorities and we accept the political realities which were created by the world and by history. All we want is to serve the good of our country in these conditions," he said.

The occasion chosen by the 39-year-old former Solidarity leader for the speech, his first since returning home to Gdansk last month, is significant. The December 1970 upheavals, and the killings of at least 55 workers by security forces, provided him with the emotional impetus to work for the creation of independent trade unions.The struggle eventually bore fruit with the birth of Solidarity in August 1980, following a strike in the Lenin Shipyard.

As an underground union activist, Walesa used the anniversary of the 1970 massacre as a vehicle for spreading his ideas. He helped organize illegal demonstrations outside the shipyard in 1978 and 1979 -- and in 1980 unveiled a government-approved monument made up of three soaring crosses in honor of those who died. He promised to return to the same spot every year, but was prevented from doing so in 1981 because of the imposition of martial law.

In his speech, he paid tribute to "the many people who gave their lives to defend ideals, the ideals of Solidarity," and added: "We who are alive are responsible before the dead for the defense of our common cause. We are accused of many things. History will judge our actions and reject slanders."

What will happen this year is still uncertain. Walesa has made clear that he will attempt to go to the monument and deliver his speech, probably on Thursday afternoon, and the government spokesman has insisted that the security forces will break up any unauthorized gathering, "whatever names are connected with it."

The possibility that Walesa may not be allowed to give his speech appears to have been what prompted him to release it two days in advance, in the hope that it will be broadcast back to Poland by Western radio stations.

The speech reflects the cautious approach that Walesa has followed since his release from internment. He avoids sensitive issues such as the Solidarity underground and refrains from advising workers whether or not to join new officially sponsored trade unions. So far, the new unions have been boycotted by a vast majority of Solidarity's 9.5 million ex-members, on the advice of the underground.

Instead Walesa, who refers to himself as "the leader of this great union which formally does not exist," concentrates on general strategy. Comparing Solidarity to a river that moved too fast along too wide a course, he suggests that "it is now time for this great social movement to divide itself into several streams."

In what appeared to be a veiled criticism of Solidarity's political goals, he said he wanted "a return to statutory activity for the defense of the working class." This phrase was interpreted as meaning that in the future, unions should stick strictly to union affairs.

Walesa added, however, that he remained committed to the right of workers to choose which union to join -- a key point in the 1980 Gdansk agreement. The principle of pluralism has been suspended at least until the end of 1984 under a new trade union law passed in October.

Another stream of the "Solidarity river" that Walesa said should now be divided was the issue of workers' self-management in factories.

"We must not force the young to live among lies, to teach them to be doublefaced in order to be successful. Perhaps the fate of Poland depends on this more than anything else," he said.

Walesa's suggestion that Solidarity should divide its forces is important because it contradicts one of the movement's original assumptions: that different social groups had to stick together to preserve their independence from the Communist regime. He now seems to be acknowledging that this obsession with unity was partly a cause of Solidarity's undoing, since the movement presented such a challenge to the state.

In the speech text, Walesa all but admitted the defeat of Solidarity as an organization -- but argued that the idea still lives on inside Poles.

"I think you can feel that. We were not able to realize our ideals in the way we planned. It is our drama that we could not this time create life in our motherland to match our dreams and our nation's abilities. Many people were disappointed, especially the workers," he said.

"I believe that the seed we have sown lies deep down. We are not the same people as we were before August. We know what to strive for although... perhaps we need more time and different methods."

[In Geneva, Reuter reported, the International Labor Organization said Walesa wrote to Director General Francis Blanchard of hopes that "it will be possible for us to resume our cooperation." Walesa led a delegation to the ILO assembly in 1981.]