Ocean Wun Zero,
Dublin Approach Radar service is carried out in the 'Dublin Control Centre', as is Shannon Apprach Radar and sometime in the future Cork Approach Radar will be there too.
Traditionally controllers were multi-rated in Tower, Approach and Ground. There was a move away from this in recent years, however due to staffing shortages, the flexibility of multiple ratings is necessary to run the place.
So it is possible to have a single rating, as some do, but you could expect to be given more than one - time and training resources allowing.