The chancellor announced a further pound;300 million to restart the college building programme in a Budget which aimed to address some of the worst of further education's funding shortfalls.
Government sources added that at least pound;1.2 billion would be committed to capital over the next five years, but colleges said many projects would still have to be scaled back or cancelled.
Alistair Darling also announced pound;251 million extra for next year's 16 to 19 funding, rising to pound;404 million the following year, to honour the September guarantee of a place in education for every teenager.
The Budget report said a "limited" number of building projects would be able to proceed from June, once the Learning and Skills Council and colleges agreed how to prioritise the 79 projects, worth pound;2.7 billion, that are waiting for detailed approval. Others would have to wait until at least 2011. The cost for all 144 plans to rebuild campuses is expected to reach pound;5.7 billion.
David Collins, president of the Association of Colleges, said: "We are very pleased that the Government has been able to find extra money in the present circumstances, although clearly many colleges will be disappointed that their plans will not be able to be funded.
"The reality is that the majority of projects will have to be radically scaled down or cancelled."
The new money may also need to cover some of the pound;220 million already incurred by colleges in planning costs, although Dr Collins said it would depend on how much authorisation LSC officials had given for spending.
But Dr Collins said the September guarantee of a place in education for every teenager completing compulsory education had effectively been saved by the announcement of extra cash for at least 54,000 places next year. "It comes as a considerable relief to colleges which are facing increasing demand," he said.
On top of the money for teenagers, pound;260 million was announced for skills in growth industries, while a pound;1.2 billion fund was intended to ensure that every 18 to 24-year-old out of work for a year or more could be given a job, long-term work placement or training.
Mr Darling told the Commons: "I am also determined that we do even more to protect young people from the damaging impact of long-term unemployment. The alternative is a return to the days when a whole generation of young people found themselves abandoned to a future on the scrapheap. We will not repeat that mistake."
But training providers said their appeals for help over Entry to Employment funding, which helps some of the most vulnerable teenagers into further training or work, appeared to have fallen on deaf ears.
A spokesman for the Association of Learning Providers said: "If they are not bailing out Entry to Employment, we would be very, very concerned. It will ensure an increase in the numbers of teenagers not in employment, education or training."