If you are determined that postgraduate study is for you, and that you want to do it for the right reasons, there are several things you can do to give yourself the best possible chance of getting onto a Masters with a 2.2 or third class degree:
Get work experience
If your undergraduate degree grades aren't fantastic, you need to do everything you can do show this isn't a reflection of your true ability.
Prove your dedication in any extracurricular way you can, such as by carrying out work experience or an internship in an industry related to your field of study.
You can do this over your summer holiday. Alternatively, you might consider taking a year out to get a job and gain some professional experience, before applying to do a Masters the next year.
Consider different institutions
Applying for a Masters with a third class degree might mean broadening your horizons slightly.
You may not have considered applying to a non-Russell Group university, but these are the ones that are most likely to consider accepting you.
Widen your mind, and consider all options when applying. No matter where they place in the league tables, every university is an institution of learning with plenty of excellent features to boast about. In fact, there are plenty of universities that accept third class degrees for Masters applications.
The more flexible and open-minded you are in your applications, the more likely you are to make it onto a Masters course.
It may be the case that by applying to the university you studied at as an undergraduate, you give yourself the best possible chance of being accepted. If there are spaces left to fill on courses, universities may be more likely to consider their own students.
Consider different courses
Instead of applying straight for a Masters, consider applying to do a Postgraduate Certificate (PGCert) or Postgraduate Diploma (PGDip). It may be that admissions tutors are more likely to consider applicants with lower class degrees for these courses, as they are usually shorter.
It may be that after successfully completing one of these courses, you could extend it in order to get a full Masters degree.
Before you apply, take a careful look at PGCert and PGDip options in your field, and whether there is potential for these postgraduate qualifications to lead to a Masters.
Take time with your application
It is important to put time and effort into any Masters application. You are likely to be competing for a place against many other people with the same qualification, as well as those with first class and upper second class undergraduate degrees.
This means you may need to work harder to convince admissions tutors that you deserve a place on their course. So make sure you sell yourself well.
Have a back-up plan
Unfortunately, getting onto a postgraduate course is much more difficult with a third than it is with first or second class degrees.
If you are keen to apply to a Masters course with a lower class degree, prepare yourself for the fact that you may well not be accepted.
In case it turns out postgraduate study isn't possible for you, make sure you have a strong back-up option ready.
This might mean applying for some jobs as well as applying for Masters courses, or perhaps looking into work experience.