Hi Rob
When I did the exam I used some charts that were not current, but they were only a few months out of date. I knew there was a slight risk of doing this but decided that I would have to be pretty unlucky to get a question which was affected by a change on the current chart.
So as long as your charts arn't too old (say more than a year out of date) you should be ok, but it's up to YOU if you want to take that risk.