London — If you live in Britain you cannot: * Know what goes on in local water board meetings. All such meetings were closed to the press by the 1983 Water Act to ''facilitate decisions.'' An amendment to open them was defeated Feb. 25 in the House of Lords.
* Know what is contained in a government report entitled ''Safety of Cyclists; analysis of the problem and inventory of measures to make cycling safer'' compiled by the Department of Transport. A citizen who tried to gain access to this report in July 1983 received a polite letter saying it was a ''restricted document.''
* Learn how many committees of the Cabinet have been set up by 10 Downing Street to argue policy issues. Nor can you learn the names of such committees, their membership, or anything about their discussions - not even whether anyone had a cup of tea during sessions.
* Obtain from the government any of its voluminous reports on consumer items - from carpets to automobiles. The government does the testing to help decide how best to spend taxpayers' money. But it will not tell the taxpayer the results in case it ''embarrasses'' any company.
A vigorous campaign is about to be launched by a number of academics, think tanks, researchers, and environmental groups to punch some holes in these screens of secrecy.
In January, a committee for freedom of information is to be announced. It is to be chaired by the director of the Nuffield Foundation, James Cornford, former professor of politics at Edinburgh University. Its chief executive officer will be Des Wilson, chairman of the environmen-tal group Friends of the Earth U.K. Mr. Wilson led a successful lobbying campaign to secure government agreement to introduce lead-free gasoline here.
No early breakthroughs are expected, Professor Cornford and Mr. Wilson said in separate interviews.
Prime Minister Margaret Thatcher opposes a US-style freedom of information act, arguing it would prevent ''good government.'' The issue is not widely debated here. Many middle- and upper-class Britons accept the tradition that it is right to leave decisions to government and Parliament.
But the campaigners, who include several former civil servants as well as the National Council for Voluntary Organizations and the Town and Country Planning Association, are convinced the issue is at last gaining popular support.
Britain, they stress, remains the world's landmark democracy, stable and solidly based. Yet they see its Cabinet style of government and its civil servants bound by a network of strict rules requiring almost total confidentiality. It is all still based, they say, on the concept held by 19th century aristocrats such as Lord Salisbury: that government must be private to be good.
In the United States, information that is not harmful to national security or damaging to individual privacy is legally available unless the government can give good reason why it should not be. The basic law is the 1966 Freedom of Information Act, as strengthened after Watergate in 1974.
In the United Kingdom, even consumer information is classified unless the government frees it.
''Here, government and civil service retain the discretion to release information or not,'' says Peter Hennessy, who covers the civil service in Whitehall for the London Times newspaper. ''The campaigners say that the public has the right to know and that the government must defend any withholding.''
The Thatcher government is watching the new campaign. With a majority of 177 seats in the House of Commons and a determination to block any legislation on the issue, it feels under little immediate pressure.
''Our long-term goal is legislation, like the US act,'' says Mr. Wilson in his two-room, third-floor walk-up office near Kings Cross station. ''But we recognize that the climate is difficult just now, and we may decide to settle for some smaller goals in the meantime.''
He says he has raised about (STR)40,000 ($60,000) so far. He needs another (STR)10,000 to meet his projected budget for the first 18 months.
Spurring him on, he says, were the difficulties he encountered in extracting data on lead-free gasoline and a recent visit to Britain by Ralph Nader.
Says Professor Cornford in his elegant Nuffield Foundation office, ''In the past, campaigners for more freedom of information have asked for too much. They've seen government as a conspiracy. Government has overreacted, by saying how appalling it would be if Cabinet discussions were revealed in the press the next day. . . .
''All we want to do is to change the presumption. Instead of the government having all discretion, the public should have the right to know and the government should have to explain any with-holding. . . .''
Professor Cornford, who helped lead a similar campaign in the late 1970s, says government must be allowed to withhold information in some cases.
''Of course, government has the right to cite national security,'' he said. ''And to protect the privacy of individuals, and stop lawbreakers gaining access to records in Scotland Yard, and protect the confidential relationship between minister and civil servant. . . .
''We don't say that more freedom of information is a panacea for all of Britain's ills. The US still has its troubles. But we do want the presumptions changed. We want the argument in the future to be over how a freedom of information statute should be interpreted. . . .''
Secrecy in the British government rests on a network of statutes and traditions that go back seven centuries. The earliest dates from about the year 1250, the origin of the Privy Councillor's oath.
Sworn by all Cabinet members in the presence of the Queen, it requires them to keep secret ''all'' matters revealed to them in their jobs, and to stay silent unless the Queen or the Privy Council say otherwise. The Cabinet is also bound by the principle of collective responsibility, or unanimity in face of Parliament. This principle dates from about 1770.
The top rank of civil servants number about 3,500. They are bound by the Official Secrets Acts of 1911, 1920, and 1939, which make the disclosure of any official information, whether classified or not, a crime.
These civil servants are also bound by a thick volume of rules originally called ''Estacode,'' or code of establishment behavior. Paragraph 9904 forbids disclosure - even after retirement - of ''any information'' acquired through an official position.
Under the Public Records Acts of 1958 and 1967, government documents can be made public 31 years after the fact - but this can be blocked if they are still considered sensitive. Some World War II documents have never been released.
In Britain, civil servants are required to be politically neutral, to serve different governments impartially, and to remain silent for life about the advice they give ministers and the reasons for policy decisions in which they are involved.
Sir John Hoskyns, a former policy adviser to the prime minister, has just stirred deep controversy here by arguing in public that the civil service urgently needs new blood if Britain is to adapt to the modern era. Sir John wants more businessmen to be drafted into office - a suggestion opposed by many, including the Times and the Guardian newspapers the next day.