You will have to have a valid class one and a class which may only be a sep class. To get an easa license issued.
The ir the old rules apply for theory.
But if the IR is lapsed you have to go to an ATO now after three months and there is recommended training before sitting the flight test even if you are flying the same aircraft for 900 hours a year. If you can find an ATO who has some common sense and is willing to ignore the moaning of the caa that they haven`t made you do the recommended training you will be lucky.
My MEP went to the wind 5 years ago and the last time i looked at getting it back. They wanted me to do the full rating again. Even though my dayjob is on a twin tp with steam instruments and no autopilot. So i reckon i would be paying to learn how condition levers work.