Thanks for all help so far. I had an offer of AAA from Corpus Christi College, Oxford, before flunking my A2s (I got straight As at AS and was predicted some A*s).
I have corresponded with Corpus again recently and they have confirmed that they are more than happy with Law as an A-level, and include it in many offers that they make to Law students. I do not know if this is applicable to Oxford as a whole or just Corpus.
I struggled with Maths for some reason at GCSE, only getting an A, although this could be more to do with the terrible teaching I received. I also hated the subject as I found it deadly dull. The suggestion of English Lit is interesting, however, again I feel that is a subject in which you have to invest a lot of time (in the texts, the contextual stuff etc). Having said that, at least I could study completely different texts.
As I say, I was looking for less taxing A-levels, in the vein of Psychology and Law. Would, for example, Economics, be less time-intensive?