It's a difficult one, as they'd generally like you to have taken your A-levels in two years (so may only count your original A-levels, the AAB). This may not always be the case though.
But law doesn't end at Oxford, Durham, LSE, Bristol etc. There are some great law schools who only ask for AAB (Leicester used to but I think they know ask for AAA. There's also Exeter - Cornwall campus). There are also some of the leading ex-polys, who can provide a great foundation for a legal career (particularly if you're aren't interested in the magic circle) that ask for ABB.
It would possibly be a good idea applying to one or two of the "top ten" law schools, particularly those that use the LNAT, and balance that out with three more realistic AAB options. Or maybe one "top ten", one solid "top 20" who still as for AAA (like Newcastle) and then three AAB unis.
Do you have any specific career plans in law (magic circle, bar, high street firms)?
Just out of interest, would you conisder a joint honours law/spanish degree (providing it's still qualifying, of course?)