Parents and staff have been taking turns to sleep overnight at the private Christian school since March in fear that the landlord might change the locks.
The north Kensington school is embroiled in a legal battle with the building's owners, a charity established by Harrow public school, which plans to turn the site into a recording studio for teenagers.
The Harrow Club said founders of the Tabernacle were aware they only had a limited lease when they opened the school three years ago, and the eviction has been backed by the High Court.
But teachers are demanding that pupils be allowed to stay on the site until new premises are secured.
Nearly all of the 41 pupils are black, and staff said many were in danger of exclusion when in state education. Students at the pound;275-a-month school follow the curriculum of the Christian evangelical group, The School of Tomorrow.
Pastor Derrick Wilson, the school's chairman, said: "Our older pupils are doing the equivalent of their A-levels now and they can't go back to state schools.
"All the pupils will be there when the bailiffs come but we are not going to barricade the door. I don't think there will be much resistance, but there might be some people trying to protect the equipment paid for with their hard-earned cash."
Although a new site has not yet been secured, Pastor Wilson has placed job advertisements in The TES for a science and maths teacher to start from September.
Harrow Club spokesman George Bennet said that Tabernacle school had been "confrontational", and was putting the club's new community projects in jeopardy.
"The club has been reasonable throughout," he said, "But the school has been squatting on the premises for a long time."
The Harrow Club was set up as an independent mission by Harrow school in 1883, but has retained close ties with the school.
Oh come all ye faithful, 9