There is really no point doing more than 4 A levels. Universities don't care and it often ends badly anyway. A friends older sister got A/A*'s at GCSE and was aiming for medicine, took 4 AS, general studies (we all had to at AS anyway), and critical thinking at school, plus another at a college in the evenings. She did badly (like C's and D's I think), dropped down to 3 for A2, still didn't do great and ended up somewhere odd through clearing doing a lame course.
Pick A levels that are tough, and if you aren't sure of which course you are going to do, chose ones with won't limit you too much (ie philosophy and law aren't needed to do it at uni, might as well do sciences/english/history).
I don't think many prestigious univerisities do criminology, I had a look on UCAS, the first one I recoguised as good was Manchester, they want ABB and didn't specify subjects. I assumed you'd be looking at the top unis and expecting lots of A's.
EDIT: if you haven't ruled out maths at Cambridge then you will need further maths. I'd advise you look through UCAS at courses and unis you might consider and see what they require.