As I can see the last time you can use them is Dec 2022 for licence issue ?
Why?
So long as you do not let your IR expire by more than 7 years they remain valid however; if you now hold a UK.FCL CPL then you will only be eligible for a UK.FCL ATPL and if you want to change to an EASA licence you may well have to take all the exams again as part of the conversion processs.