Law and Psychology will not be too much of an issue, Sociology has never been looked at well. Some unis are fussy and accept only certain A levels but most are quite flexible bar Oxbridge and the top London unis etc. Southampton ask you to take 2 traditional subjects for example. I'm starting Law at Uni of Manchester in 3 weeks, they welcome all A level subjects, but do have certain grade requirements for GCSE Eng and Maths. On the whole it is advisable to do Eng Lit and History as they are essay subjects and you need strong writing skills for Law. Did Eng Lit, History and Law at A level myself.