If the plan goes ahead, Iraqi leader Saddam Hussein would get a few more days to prove that he is disarming.
But it would be a matter of days, rather than weeks, the United Nations said.
Is Saddam trying?
The United Nations, which revealed Britain's plans, said Iraq would be expected to work closely with their weapons inspectors, who are in Iraq now, during this time.
Meanwhile there are anti-war protests going on all around the country - many from students and school children.
The head of UN weapons inspectors, Hans Blix, is due to give a report on Friday about Iraq and he's expected to say Saddam's tried harder to work with them in the last few weeks
But American military bosses don't agree and they say Iraq is deceiving the rest of the world about what weapons it has.