WB the lawa has changed now, so if you do go round to your mates house more than 4 days a week for a certain amount of hours (cant mind off top of my head what it is) you do have to be CRB checked !!!
I had to have CRB check for helping cook breakfast for the scouts before they went on a hike for the day
and for being a school governor, which doesnt actually involve much if any contact with the kids !!!