If you wish to have a career in academic law, you could start with a PGDL, but I suggest that you consider instead obtaining a senior status degree in law after completing your degree in English. This would take you two years after graduating, and might make you a more competitive candidate than a PGDL. You would then need to continue studying as a postgraduate with a view to obtaining first a Master's degree and then a Doctorate in law, and once started on a doctorate you could apply for junior academic posts.