CPL exam passes are valid for 3 years for CPL issue. They are not valid
at all for IR issue.
ATPL exam passes are valid for 3 years for initial IR issue.
Provided an IR is maintained then ATPL exam passes are valid
indefinitely for ATPL issue.
If no IR is maintained then ATPL exams remain valid for 7 years from last
date of holding a valid IR, for both IR renewal and ATPL issue.
With the new Competency Based IR (with its one exam) on the horizon it is
probably not worth doing ATPL exams if an FI is all that is wanted now - with
achieving an IR to be decided later, and possibly not within the 3 year exam
pass window.