You can't take an ATPL.
You can get frozen ATPL. ATPL theory + CPL/IR/ME JAR.
Frozen ATPL becomes ATPL when you pass 1500 total time (however requires many different categories of flying hours, to find out more check JAR Air Law)
It is complicated, you can only achieve ATPL after you have plenty of flying experience, in various conditions that apply. Do some research first on the topic.