Young people are becoming more sceptical about the benefits of going to university, despite a large majority saying they want to carry on to higher education, research suggests.

The findings coincide with the publication on Thursday of A-level and BTec level three grades for hundreds of thousands of sixth formers. University admissions offices were braced for a flood of enquiries after more than 600,000 candidates applied though the Ucas process this year.

Thanks to a rapid expansion in the number of university places available in recent years and a slight fall in the number of applicants overall, a significant number of courses still have places available. More than 26,000 places are on offer through the clearing system at universities in England alone, including some belonging to the Russell group of leading research institutions, according to the Press Association.

The new research, carried out by Ipsos Mori for the Sutton Trust, polled 2,300 English and Welsh pupils aged 11 to 16.

It found that 75%agreed it was “important” to go to university, down from 86% in 2013.

More than three-quarters of those surveyed said they were likely to go to university, although the number of those who said they were “very likely” to go slipped from 38% in 2013 to 32% this year.

The Sutton Trust charity promotes social mobility through education. Its founder, Sir Peter Lampl, said it was no surprise to see the fall in enthusiasm tempered by the realities of being a student.

“Young people face a dilemma,” he said. “If they go on to university they incur debts of over £50,000 and will be paying back their loans well into middle age. And in a number of cases they end up with degrees that don’t get them into graduate jobs.

“On the other hand, degree-level apprenticeships are almost non-existent, with fewer than 10,000 available each year compared with over 300,000 university places. There is effectively no viable alternative to university.”

The polling found that those from the least well-off families in England and Wales were the most worried about the cost of studying. The Sutton Trust wants the government to restore maintenance grants and consider means-testing tuition fees to reflect the financial circumstances of young people.

Alistair Jarvis, the chief executive of industry body Universities UK, said that demand for university places was at record levels among school-leavers. “A university education is an excellent investment which can have a transformational impact through the skills and experiences graduates acquire,” Jarvis said.

For most sixth formers their immediate concerns would be their exam results, with particular interest in England, where students will be sitting the latest tranche of reformed A-levels in subjects including religious studies, modern languages and geography.

The last batch of reformed subjects – in which grades would in most cases rely on final exam marks rather than continuous assessment – follow the 13 that were sat for the first time last year, as part of a drive by the government to make the qualifications more challenging.

“The new qualifications remain of the same high standard as the ones they replaced and have been updated with input from universities,” said Sally Collier, the head of England’s exam regulator Ofqual. “They have more effective assessment arrangements and also allow additional time for study.

“Against this backdrop of change, it is pleasing that the exam series has gone smoothly and that standards have been maintained. Students, schools and colleges should be congratulated on their achievements.”

Ofqual has said that overall the proportion of grades awarded would be little changed from previous years despite the change in exam formats, which have seen AS-level results excluded. The proportion of grades awarded has been set using the prior attainment of pupils taking exams in each subject, based on their GCSE grades.

However, Collier has warned that the distribution of grades may change, with schools likely to see some volatility compared with previous years. Boys may also improve their performance relative to girls’ for the second year in a row, with boys thought likely to do better in exam-based assessments.