Correct you dont need a valid rating on your UK licence.
To convert to easa you need a easa medical,pass the Test of English aviation and send your old licence.
To revalidate your rating or transfer your icao rating to a easa,you will need to go via an ATO.They will let you know how much training if any is required depending on when your rating was expired and whether you are current in another icao member state or not.