Britain holds back from invasion -- a lull before storm?

Despite the limited naval bombardment of Port Stanley, Britain is holding back from an all-out invasion in the hopes of a negotiated peace. But there is a growing feeling that this period of restraint could well be the lull before the storm.

The government of Margaret Thatcher stands resolutely opposed to any suggestion that it agree to a cease-fire before Argentina has at least begun to withdraw from the Falkland Islands. Mrs. Thatcher used tough language in the House of Commons May 11.

The prime minister said a cease-fire must be accompanied by a withdrawal before long and under no circumstances would sovereignty be ceded to Argentina in advance.

The withdrawal, which Britain may be prepared to accept in stages, must be supervised by an international body. Britain makes it clear this body should have United States or other British allies in it, and not just be made up of nonaligned countries which might be inclined to take Argentina's side in the dispute.

Underlying the British standpoint in recent talks at the United Nations has been a flinty view that Argentina is not about to yield, combined with a degree of flexibility on what London might agree to after a withdrawal.

Meanwhile, the prime minister is refusing to yield on two other fronts -- military and political -- even as the crisis reaches into new areas. The crisis has raised doubts that the Pope can visit Britain next month if the country is still fighting Roman Catholic Argentina. And it seems likely that government pressure on British soccer players will build -- pressure to pull out of the World Cup, because Argentina's team, the current world champions, will be taking part.

* The military front:

The British task force keeps shelling the Port Stanley area before dawn to demoralize Argentina's conscript troops and demonstrate its own determination to enforce the blockade zone.

Officials say the shelling of an Argentine supply vessel by a British frigate in the sound that separates East Falkland from West Falkland Island shows how alertly the task force is maintaining its control.

Britain regards Argentine reports of this and other incidents as being exaggerated with the aim of making Britain appear as the aggressor during talks at the United Nations.

Some light Argentine planes have penetrated the blockade, and analysts say at least one Hercules cargo plane has dropped supplies by parachute. But major resupply seems to have been prevented.

If the UN talks break down, or if Prime Minister Thatcher suggests Argentina is simply trying to keep talking without meaning to withdraw, the Cabinet is expected to order the task force to occupy parts of the West Falkland coastline and high ground.

If that did not persuade Buenos Aires to withdraw, Mrs. Thatcher would order more bite-by-bite occupations, perhaps even an attack on Port Stanley itself. But she would need the new supplies of men, helicopters, and Harrier jets that are on board a reinforcement fleet now approaching the war zone.

It was to slow those reinforcements down, or to deter them altogether, that Argentina has announced a naval blockade of its own. It says any British ship anywhere in the South Atlantic is likely to be attacked.

Argentina sees time on its own side. Winter weather is worsening. Yet the British believe their fighting forces, all professionals rather than volunteers, are much superior. They say more Harriers can fly from Britain, given in-flight refueling techniques.

The greatest British problem, according to US sources, is a lack of depth. If it loses just one of its two aircraft carriers, for instance, or two or three more escort ships, the task force would be in serious trouble.

* The political front:

The government insists on retaining freedom of action, despite Labour Party efforts May 11 to allow the House of Commons to debate any UN peace proposals before the Cabinet acts on them.

Labour leader Michael Foot fears Mrs. Thatcher will escalate the fighting before the UN has had a full chance. So far, public opinion seems to support Mrs. Thatcher, and Mr. Foot is deep in dispute with his own moderate and far-left wings.

His party chairman, Dame Judith Hart, wants no more escalation at all but a cease-fire. And Tony Benn calls for the task force to be stopped at once and no more lives put at risk. Labour is split several ways. That makes it easier for Mrs. Thatcher.

Another sign of how unsettled many people are by the crisis is a heated public dispute about the way British newspapers, radio, and television are covering the fighting.

Mrs. Thatcher agreed May 11 with Conser-vatives who attacked the BBC for giving too much credence to Argentine reports of the fighting and not enough support to the British view.

Meanwhile, Mr. Foot defended the right of an independent press in a democracy but condemned in the strongest terms the ''hysteria'' of two pro-Conservative newspapers, the Sun and the Daily Mail.

The families of some men in the British task force have complained the BBC treats British and Argentine war claims as equal. The BBC denies any anti-British bias.

A BBC television program May 10 that presented both supporters and critics of the government policy was condemned as a ''sort of treachery'' by a senior Conservative figure May 11.

Mrs. Thatcher urged critics to write directly to the BBC. She agreed, too, that a free society must have an independent press, but she said the press should temper that independence with an obligation not to provide the enemy with information.

In reply, many newsmen say the government has mishandled the propaganda war. No British film from the war zone has been seen here, and control of information is stiff.