If you are uncertain of what to study a gap year would definitely be a good idea as you might get a better idea of what you love to do and it definitely would not hold you back (employers love a well travelled applicant as it really does broaden your mind). However, just on a side note, the subject you do at university if not as limiting as you might think, hardly any of my friends are now in jobs relating to their subject! Psychology shows a very high level of intelligence and analytical skills so it is a great degree for your cv even if you decide you don't want to pursue a career in the area!