We have had very positive experience of people entering the profession later on. If you have been applying to clinical psychology for some time and have good experience, it may appear to the selection panel that your more recent experience has not strengthened your application. For example, a third year as a psychology assistant added to essentially the same application will not make you a stronger candidate than last year and, with each year, the effort you put into gaining experience will reap diminishing returns. A long gap since your first degree is a disadvantage, particularly in the absence of evidence of continued academic interests. Try to get some frank feedback from people who know your work well.
Additional degrees are by no means the norm among applicants.
Some obtain a masters degree to enhance their application and there is no doubt that a relevant qualification provides further evidence of your academic and research ability. Make sure that you are happy with the content of a Master s course before accepting a place. Clinical experience is still essential. An additional degree will not compensate for a first degree which is lower than a 2.2. Completing a PhD just to apply for clinical psychology is a long route into the profession.