The independent school, which opened in 1993, learned just before Christmas that ministers are minded to approve its bid for state funding. It originally bid for grant-maintained status in 1994.
The 220-pupil college's intake ranges from nursery age to 18. It now plans to split into a separate primary school of 200 children and a secondary school of 450, including a sixth form of 150.
Delighted headteacher Rajinder Singh Sandhu, who will take charge of the secondary school, said: "It already looks like we will be absolutely full. We were the very first Sikh school and now we are to be the first to get voluntary-aided status."
Earlier in December, the Association of Muslim Schools won permission to set up a teacher-training course.
The Government gave grant-maintained status to two Muslim schools in January 1998 after a 15-year campaign making them the first non-Christian or Jewish religious-affiliated schools to win state funding. This was followed by the award of state funds to a Seventh Day Adventist school, John Loughborough in north London.
Guru Nanak College in Hayes serves most of west London, including the large Sikh community of Southall, one mile away. Some students commute from Reading and Luton.
It is named after the founder of the Sikh religion, and an extended school day, running from 8.30am to 4pm, allows it to teach the Punjabi language and Sikh culture and history alongside the full national curriculum.
The college was founded by Sant Baba Amar Singh Jim, the community's spiritual leader, whose charity Nanaksar Thath bought the disused Walsingham RC secondary school from the Diocese of Westminster for Pounds 1.1 million.
Until now it has survived on fees of Pounds 1,300 a year and strong community support. Although schools minister Estelle Morris gave her backing for VA status two weeks ago, it depends on final assurances and a date has yet to be set for the switch from independent to state sector. September is the most likely date to minimise disruption.
The school has already linked up with Manchester Metropolitan University and Uxbridge College to gain qualified teacher status for staff who have not yet gained it.
The campaign has had the cross-party backing of Hillingdon Council - into whose fold it will come - and Hayes and Harlington Labour MP John McDonnell who met Ms Morris to push the school's case.
The school already has a successful track record. This year it came third in Hillingdon's GCSE tables with 73 per cent of pupils getting five passes at grades A*-C.
At present there are some 7,000 religious-based state schools in England,including 4,800 Church of England, around 2,000 Catholic, 55 Methodist, 29 Jewish, two Muslim and one Seventh Day Adventist school.