if you look at the police.uk website you can put in a general area i.e. SE23/SE26 and se the crime rates over the last few months and then you can also see the crime rates and types of crime for each street. It will give you info on the local neighbourhood police and you can then phone them and ask for their perspective. They can be very helpful and will always say " this is London and there is always more crime than the rest of the country" but can be quite reassuring overall!