Is today the one-day air traffic controllers' and weather forecasters" strike? No, that was last weekend and it kept millions of business people and vacationers from entering or leaving Britain.

Then is it the beginning of a series of national one-day strikes by more than two million engineering and electrical workers that threatens 650 manufacturing firms and the country's electrical power system? No, that's still a few weeks away, and could be avoided if the unions are given a better pay-raise offer.

What about the London subway strike? No, that one was avoided for now by a higher pay offer although service is still disrupted almost every day by normal staff shortages and people who just don't show up for work. Check the chalk board in the subway station to see if the trains are running on time today. Same goes for British rail commuters' trains.

Are clerical workers still on strike at Labor Party headquarters? That's just too politically embarrassing for both the unions and the party they support to continue.

Oh yes, of course, it's the strikes by the civil servant unions at the post office, which in Britain is in charge of both the mail and the telephones. That's why the Post Office asked everyone in Britain, and especially London, to stop mailing letters for a while, why it's impossible to get a telephone installed, and why the quarterly bills for people with telephones have not come out for months.

The civil servants are ingenious strikers. Instead of pulling everybody off the job throughout the government all over the country, they specialize in hit-and-run strikes in selected sensitive parts of the giant government machine. The strikes are small, but their effects are big.

Today, for example, just five people who are in charge of distributing stamps to all of Britain's Post Offices are going on strike. If they stay out,as their union vows, there won't be any stamps in any Post Office in just a few weeks. In London, where stamp volume is greater, the shortage could be felt by the end of next week.

London already is suffering the worst effects of other disruptive labor actions and a growing staff shortage in the Post Office. With mountains of unsorted mail building up, the Post Office can't take any more. If people do not heed its plea to stop mailing letters, it may do what it did only a month or two ago: close the openings on most mail boxes so that people are physically unable to mail letters.

A strike by just 650 more civil servants who normally run the computers for the telephone company part of the Post Office has stopped the flow of telephone bills to customers and money back to the Post Office. That strike, other "job actions" and staff shortages also have delayed installation of new telephones for months into the future. Businessmen who move offices or build new ones here cannot get telephone or other communications equipment installed or hooked up to the telephone lines for up to two years, which is beginning to discourage some businesses from moving to or staying in London.

And, it's only summer. The really big, disruptive strikes come in autumn and winter - like the trucking, auto plant and local government workers strikes last winter that helped defeat the Labor Party in last month's national election here.

Already there is talk of more strikes this autumn and winter because the unions are unhappy with the economic policies of Prime Minister Margaret Thatcher's new Conservation Government and believe their members must get really large pay-raises - 20 per cent or more - to cope with the fast-increasing rate of inflation here.

The civil servants who, beginning while the Labor Party was still in control of the government earlier this year, have hit with selective strikes everything from the Post Office, airports and computers that run much of the government to naval bases and munitions factories that make the army's bullets, want pay increases up to more than 30 per cent. So do the engineering and electrical workers who are threatening to cripple much of British industry.

Clearly salaries are low now in places like the profit-making Post Office, Europe's largest single commercial employer (although it's government-owned) where many people still work a six-day week. The unions say the low salaries, long weeks and over-night shifts are the reasons for the serious staff shortage, in a time of rising unemployment, and that the staff shortage is the real cause of the rapid deterioration in mail and telephone service. Transportation union leaders say these same problems are responsible for the staff shortages that disupt subway and train services.

Lower salary union men also are unhappy that Thatcher gave big raises of 25 to 35 per cent and more to the military, police, national health service doctors and dentists, and top government officials right after becoming Prime Minister. They also are not impressed by her tax system, in which upper income families, including families of higher paid union-member skilled workers, got the biggest income tax cuts while everyone has to pay much higher sales taxes.

Leaders of the Trades Union Congress, Britain's more widely representative counterpart to the AFL-CIO, told Thatcher just that at their first meeting this week with the Prime Minister since she took office. They also complained that her planned cuts in government spending and selling of some government-owned industries threatened to add significantly to Britain's already rising umemployment rate.

They told Thatcher they did not think her intended shift of the economy from heavy government involvement to greater private enterprise would work, and that her shift from income tosales taxes would not eventually make everyone better off as she believed it would.

Thatcher told them she agreed that increasing inflation (over 10 per cent now and expected to reach nearly 20 percent by year's end) and unemployment (heading towards 1.7 million next year out of a labor force of 270 million) were worrying problems. But she said that more jobs could be created and wages raised only if everyone worked harder to expand the British economy. And excessively high wage demands and settlements, she again warned pointedly, could only lead to the loss of more jobs in an economy as static as Britain's at the moment.

So the labor leaders decided to take their case to the public, as Thatcher successfully did during the election campaign. They said they would mount their own national campaign to win public support for the government-run economy and expanding welfare state from which Thatcher wants to move Britain away.

They say they are not seeking a nasty confrontation, although individual unions may strike for wages high enough to stay ahead of inflation. Thatcher and her lieutenants have also said they do not want a confrontation, and they have decided to wait several months before trying to legislate changes in British labor law that would curb some of the unions' powers.

Conflicts with labor led to the election defeats of the last two governments here, one Conservative and one Labor. Former Labor Prime Minister James Callaghan, the most recent loser, has warned the trade union movement on which his party is based that it should not try non-democratic means to bring down an elected government it does not like. Besides, Thatcher has a much safer majority in Parliament than her two predecesors had.

The outcome of the evident maneuvering by both sides may be decided this winter, unless this summer's steady trickle of inconvenient strikes escalates sooner into the confrontation everyone says they want to avoid.