Prime Minister Margaret Thatcher today unveiled her plan to begin moving Britain away from socialism by cutting income taxes, reducing government's role in the economy, reining in labor union and "restoring choice to the individual."

The new Conservative government's blueprint for change was outlined in a traditional address read by the queen in her sequined gown and heavy, bejeweled imperial crown to the ceremonial opening of Parliament.

Thatcher, Britain's first woman prime minister, later supplied details in her first major speech as prime minister in the House of Commons, the lower chamber. Among the more significant of her plans are:

Immediate cuts in income tax rates and public spending in the budget her chancellor of the Exchequer, Geoffrey Howe, will present to the House of Commons on June 12

Sale of profitable governmentowned businesses to private investors, and less, if any, further nationalization of industry.

Sale of public housing homes and apartments to the families living in them at discount prices.

Retention of elite public schools for bright students and grants to help middle class parents send their children to private schools.

More opportunity for those who can afford it to pay for speedier private health care through private health insurance rather than the overloaded National Health Service.

Legislation to prohibit secondary picketing by labor unions, to lessen the impact of closed shops on nonunion workers and encourage secret ballots to make union decisions.

Immediate large pay raises for police officers and soldiers, and improvement of Britain's nuclear arsenal.

Stronger ties with Europe, but a better economic deal for Britain from the Common Market.

Consultations with the United States, Europe and Commonwealth nations before action on Thatcher's commitment to recognize the new biracial government in Rhodesia.

Thatcher thus has put on the agenda for her Cabinet and Parliament for the 18-month session beginning today at least a major first step toward fulfilling each of the Conservative Party's promises during the compaign for the national election it won less than two weeks ago.

Some steps that do not require legislation have already been taken, including raises for police officers and soldiers, and the administrative preparation for selling hundreds of thousands of public housing units to their tenants at big discounts. Others, including income tax and public spending cuts being decided by the Treasury, will be included in the budget next month.

Thatcher's promised turn to the right for Britain was introduced with customary blandness in the short speech her aides wrote for Queen Elizabeth II, who read it in a detached monotone to members of Parliament, judges, royalty, diplomats and guests crowded into the House of Lords chamber.

The queen went to Parliament's Westminister Palace on the bank of the Thames from nearby Buckingham Palace in a ceremonial procession of horsemen and centuries-old carriages.The leading peers of the House of Lords wore scarlet robes trimmed with ermine and gold, and their ladies in evening gowns flashed diamond-encrusted tiaras and necklaces.

When the Commons reassembled this afternoon to hear Thatcher and former prime minister James Callaghan, now the opposition Labor Party leader, open debate on the Conservatives' legislative program, Thatcher demonstrated that she had lost none of the fervor of her crusade against socialism during the election campaign.

With notably more confidence and emotion than she had shown in parliamentary debate as the leader of the Conservative opposition for four years, she heatedly denounced Callaghan's accusations that her proposals were "negative and devisive" and "the society the Tories wish to create is, 'What's in it for me.'"

Reminding Callaghan that the Conservatives won a handsome victory in a "watershed election," Thatcher said, "You can't sufficiently help the unfortunate members of society if you don't give sufficient opportunity to the able."

Thatcher intends to begin doing that by reducing income taxes and shifting some of the burden to sales taxes. The basic income tax rate is expected to be cut from 33 to 30 percent and the top rate for high incomes from 83 to 60 or 65 percent. The value-added sales tax is expected to be raised from 8 to 10 percent.

Thatcher said she will abolish Britain's Price Commission, which she said had destroyed jobs and new investment with lengthy bureaucratic investigations and prize freeses. Legislation would be introduced instead to increase the power of the Fair Trading and Monopolies Commission to investigate competition-inhibiting monopolies, including monopolies owned by the government, she said.

Small businesses would be encouraged, Thatcher said, by the income tax cuts, less government red tape and repeal of a job protection law that the Conservatives contend inhibits small businesses from hiring new workers by making it almost impossible to eliminate their jobs later.

Thatcher put great stress on "restoring the choice of individuals" by helping public housing tenants buy their homes, making private health care easier to use, and maintaining a choice in education among comprehensive public schools, elite "grammar" schools for bright students and private schools for those willing to pay tuition.

The legislation to prohibit secondary picketing, compensate workers who lose their jobs because of closed shop agreements and provide government money for secret balloting by mail for union decision-making will be introduced before Christmas, Thatcher said, after lengthy consultations with labor leaders. She indicated that more actions to curb union power-including a restriction on the amount of government benefits to families of striking workers-would follow later.

In her most important foreign policy pronouncement, Thatcher outlined a cautious timetable for action on Rhodesia. Nothing that her government "welcomes the major change that has taken place in Rhodesia as a result of the recent election there and the emergence of an African-majority government," Thatcher said: "It is our intention to build on that change, to achieve a return to legality in conditions which would achieve wide international recognition."

She expects to receive a report on the Rhodesian election from her team of observers Wednesday and already has sent a senior diplomat, Anthony Duff, to Rhodesia to confer with the new biracial government's leader, Bishop Abel Muzorewa. Next will come extensive consultations with the United States, (beginning with Secretary of State Cyrus Vance's visit here next week) Europe and the Commonwealth nations. CAPTION: Picture 1, Queen Elizabeth, with Prince Phillip at her side, reads her speech from throne. UPI; Picture 2, Prime Minister Margaret Thatcher brushes speck from suit of arts minister. AP