The best schools of architecture in terms of the quality of work, employers opinions and competition for places are:
UCL
Sheffield University
Glasgow School of Art.
Bath, Cambridge, Cardiff (and maybe the AA) are also very well respected. Westminster seems to have won a few of RIBA awards recently but there seems a greater difference between the best and worst work than other schools and student dropout and satisfaction is not so good. It all depends what u are in to really, some schools put greater emphasis on design, some on CAD, some on engineering, others on environmental stuff. You can study without A level art but many of the best schools base their decision on a portfolio because of the number of applicants with 3As+ so it is important to be creative and imaginative.