Doing 3 AS levels complicates things a little; my college, and the majority of colleges I believe, recommend studying 4 AS levels unless you are absolutely certain you'll enjoy and do well in 3. This then gives you the ability to simply drop one in second year.
Are you planning on going to uni?
You could do the english exam this year then take up another AS level next year, giving you 2 A2s and 2 ASs. This is probably the easiest thing to do, however most unis require 3 A2s.
You could drop english and do a full A level next year, so you'd have 3 A2s and the AS. This should be ok to get to uni, however the workload could be very demanding and it is not easy, so you would have to ensure your grades don't suffer.
You could also do a 3rd year at college. Do all of your exams this year, media A2, sociology A2 and another AS next year, and do the A2 in the new subject either part-time (if your college will let you, or as an independent student) or with a couple of extra courses in the 3rd year. However this could limit your uni choices as most require you to sit all exams within a 2 year period (this definitely relates to the Russell Group unis, and a few others I believe)