The 32 pupils and two teachers at the private Ysgol Gymraeg Llundain school move out of their former chapel in north west London today. As the Buddhists plan to set up their own school, the Methodist-run Welsh-language school needs other accommodation.
Cash constraints have left the school with few options. It has been paying a peppercorn rent on the chapel building and survives on pound;500-a-term contributions from pupils' families, grants and fundraising.
Trustees have appealed in vain for help from the Welsh Asembly, the Department for Education and Employment and local education authorities.
But a last-minute deal with a primary school in Harlesden which has an empty annexe with its own entrance and play area, could secure its future.
Head Sian Edwards is expecting an answer today: "It was initially hoped that the school could use rooms at the back of the building but the new owners have decided members will use them for religious study.
"We have our fingers crossed about use of the primary school."
The school is the only one outside Wales which teaches in Welsh. The 16 full time and 16 part-time pupils come from all over London and beyond to attend.