I don't think I personally heard of A2s, there are only really A level, I am from Scotland so I am not sure, where I come from Advanced Highers are the highest national education certificate High Schools offer which is equivalent to A levels, however, there are higher national diplomas and higher national certificate. If you meant A2 as in the grade given in A levels then I guess that's what MOST (not all) universities in the United Kingdom want to see, it all depends on what you want to study. For medicine, just go no-kill all A levels and A grades. However for other universities, I have seen B grades and even Cs for some with A level, GCSE/National 5 etc. Whatever your college is offering should be up to standards and following your curriculum, by law, and that means you should have the experience, and a certificate to show your employability or/and personal knowledge and skills. So don't worry everything will work out!