JAR PPLs had a validity. The OPs licence has definitely lapsed pilotjimbo, not just the rating. He needs to go to a Head of Training for an assessment of minimum training required, before an LPC with an examiner and an application for an EASA PPL, or LAPL.
...is the correct answer!
The assessment and associated refresher training may
all be conducted at a RF - there is no need to go to an ATO. The associated forms may also be signed off by the RF.
Don't forget your FRTOL and English language proficiency requirements!