I think that the UK CAA exams explicitly say that you need a UK Chart to sit the exam.
(This is either the southern or northern England chart - both Airquiz and the CAA exams have set the questions relative to things on the overlap between the 2, presumably so that neither southerners nor northerners can complain that they are discriminated against. As long as you're not Scottish...)
I thought that CATS material for self-study should be self-sufficient.
If they told you that was the case even when you did UK CAA exams and they have not provided a chart, you may want to take it up with them.
In the meantime, a chart is about £15 and easily posted, so in the grand scheme of things...
B.