Charities insisted that proposals to confine the exemption to students who had arranged voluntary work for their year out by 23 July - the date ministers announced plans to introduce fees - would catch out thousands of well-intentioned potential volunteers who would only make arrangements in the autumn.
Without this waiver, such students might decide to seek a university place this year instead or might look for paid work to help ease future debts, charities fear.
The Community Service Volunteers, which places some 1,200 school-leavers annually on projects helping young offenders or children struggling with reading, warned of a "risk that the energy of young people could be lost".
The groups also renewed pressure for an extension of special deals for gap-year volunteers beyond next year - a step understood to be looked on favourably by David Blunkett, the Secretary for Education and Employment. Charities want students who commit a significant portion of their year out to volunteering to be exempted from a year's tuition fees - equivalent to pounds 1,000. Voluntary groups made their case as Department for Education and Employment officials rang round those accepting high numbers of gap-year students, asking for views on the terms of the proposed fees exemption.
Following concerns that students intending to take a year off would rush for university places this year to avoid fees being imposed from 1998, it emerged that the Government proposes to allow students holding a deferred place and planning at least three months' voluntary work to be exempted from the charges.
However, questions still remain over the detail of the fee waiver plan. Yesterday's consultation - in preparation for a formal announcement at the end of the week - drew accusations from some voluntary bodies of "policy- making on the hoof".
The CSV insisted any exemption should include all students taking a year out, regardless of whether they already had a university place for 1998, and should cover anyone volunteering for at least four months during the year.
Executive director Elizabeth Hoodless said: "The reality is that young people don't plan ahead. To drop a line at 23 July is to punish all those who haven't got round to arranging voluntary work yet."
CSV gets most inquiries from gap year students in the autumn, as does the Prince's Trust, one of the charities cited as an approved organisation whose volunteers would qualify for exemptions. The Royal Society for the Protection of Birds, which takes on volunteer wardens, also usually hears from students in September.
Gap Activity Projects (GAP), which will send over 1,300 gap year students to do voluntary work in 30 countries next year, also pressed for an extension of the fees waiver to aspiring students without a deferred place.
Some universities and some courses refuse to allow would-be students to defer places, forcing them to apply during a gap year.
The DFEE consultation also concerns the amount of time students are being asked to devote to voluntary work in order to become eligible for a fees waver. Charities have been asked whether they think three months is long enough or whether four or even six months would be more appropriate.
Why Chi had to shelve his plans
When Chi Cheung (right) heard the Government proposed charging students fees and abolishing grants from next autumn, he changed his plans. He had a place at London University's School of Pharmacy from next September but decided to go this year. He had planned to work for a year in the University of Hertfordshire library. "People are talking about students leaving with a debt of between pounds 5000 and pounds 8000. That might double or treble if I don't go now. Living in London is very expensive.
"I can understand why Sir Ron Dearing made his proposal to charge students fees. Something had to happen but I don't want it to happen with my future."
Chi, 20, got A-levels in maths, chemistry and biology the year before last but felt he needed time to decide what to study.
He regretted telling the library he would not be able to continue there but decided he had no choice.
`I can't afford to work for charity'
If Lily Williams had known about the Government's decision on tuition fees, she would have applied to university this year. As it is, she has offers of places at Sussex and East Anglia for next autumn but did not apply this year to her first choice, Edinburgh, because it does not accept students a year in advance.
She still wants to go to Edinburgh to read history and politics and intends to continue plans to teach English in Spain. She believes the fees concession which will exempt students who work for charity during their gap year is wrong. "I don't have enough money to keep myself and work for charity. Anyone who can afford to work for charity for three months is likely to be better placed to pay tuition fees."
As a first-time voter who supported Labour and voted tactically for the Liberal Democrats, Lily, 18, who attended Cherwell comprehensive school in Oxford feels disillusioned.
Adele Walker (right) made up her mind to take next year off before university last spring, when six applications for performing-arts degree courses produced no offers she was happy with.
Three weeks ago she learned her decision to reapply would cost thousand in fees, a bleak prospect for an aspiring actress seeking to enter a poorly paid profession.
Adele, 18, who has just done a BTEC qualification in performing arts at Wilmorton College, Derby, considered joining the scramble for places this autumn through the clearing system but decided to stick with her original plan. "I am not happy about having to pay fees ...But I can't just readjust everything or change my career plans because of this. I am not going to rush into clearing and get on a course I don't really want when I have wanted to be an actress since I was 13."
Adele has already begun seeking acting experience for her year off to boost her CV.Reuse content