There is an awful lot here:
http://ico.org.uk/
snf on the right of the screen - you will see a topic guide.
I THINK you are obliged to tell people, and where to get the data if they want it ( you ) . It is obvious you arent only using it to detect crime so the usual law applies. [ oddly enough if it only for crime, then I think you dont have to ]
while you are at it - wonder if you are keeping named data on your computers and if you are, then think about registering as a data provider.
( I do both ). [Most professions have a computer users section. for about ten years I was the only member of a committee who had registered.....]
It is no big deal if you dont - but I think the £35 is well spent....