For thousands of teenagers across Sussex, today is the day of reckoning.

Two years of work and months of agonising are finally over for students who sat their A-level exams during the summer.

Today, as they anxiously rip open their results' envelopes, they will learn if their dreams for the future are set to become reality.

However, while some crack open the champagne, others will be forced to reassess their plans if they did not get the grades they needed to get into their desired university.

For students who only just missed the grade, it is worth calling the university or college concerned to find out if they still qualify for a place on their chosen course or can change subjects.

If they are refused, they must decide if they want to resit their exams or find another institution willing to accept their grades as they stand.

To do this, they will need to go through the University and Colleges Admission Service (Ucas), which runs a scheme called clearing.

The idea behind the scheme is to help applicants who did not get into their first-choice university to obtain a place elsewhere.

Clearing is not a market place for unwanted courses. Most universities, even the most prestigious, advertise course vacancies through the system. Last year 40,000 students found places through clearing.

All Ucas applicants who have paid the £15 application fee and have not had a place confirmed following release of their examination results are entered for clearing. The onus is on them, however, to contact institutions for places directly.

Vacancy lists will be posted on the Ucas web site and help will be on hand at colleges and sixth forms.

Clearing carries on into September so students should not feel forced into making a decision, although moving quickly to secure a place can be an advantage.

For students unsure about their next step or considering dropping out of higher education altogether, help is available from the careers service Connexions, which operates 35 centres across Sussex.

Chris Andrews, chief executive of Connexions Sussex, said: "It is vital young people who haven't gained the results they were hoping for look at it as an opportunity to reconsider what is best for them.

"Our personal advisers are there to work through the many exciting opportunities available, be it university, work-based training or modern apprenticeships."

Chris Manley is a personal adviser based at VT Careers Management West Sussex in Worthing, which is part of the Connexions network.

He said the most important thing was for students to be calm to ensure they made rational choices.

He said: "The key is not to panic and to talk to the people who can help.

"They should not be afraid to ask for guidance from people at college or school.

"They can help students consider all the options before jumping in.

"We can talk to them about the state of the local jobs market, advising them on what sort of careers will require degrees.

"If someone decides they want to be a fashion designer, for example, but they don't want to go to university, we can tell them that would be a mistake."

Universities in Sussex are also gearing up for their busiest day of the year.

Thousands of students will be seeking places at University College Chichester (UCC) and the University of Brighton through clearing, while others who got grades below expectations will be frantically ringing admissions tutors to find out if they still have a place.

UCC has a list of 124 courses on offer through clearing, which has already been posted on its web site.

The University of Brighton likewise has a list of about 200 vacancies on its web site.

The University of Sussex has no free spaces available through clearing so far, with more than 2,000 students having been offered conditional places.

Applications to the university were up by 17 per cent this year, compared to a national average of about 3.5 per cent.

Students with questions about exam results can visit a new web site titled Exam Zone, which has been set up by exam board Edexcel.