You will need to contact an
FIC provider and complete training as required to pass the FI Test with an FIE. You also have to attend a FI Revalidation Seminar, these are held at regular intervals by
AOPA and
ONTRACK On completion, the CAA will have to reissue the rating as it has expired by more than 5 years. At that point, there will be some options regarding an EASA licence, as you say you have a UK ATPL and that will not be valid on EASA aircraft after April 2014.