Not sure what you mean by 'modern version' Betsy but most hardwares or Woodies and the like would supply these.Bring your old one back as you'll be paying the Weee charge anyway and they'll dispose of it for you.
I don't have an old one, it's for a new house. I thought maybe an updated version with chrome or something, not the plain plastic industrial looking one my mother used to have.
Not in Ireland!. They are hard to find, if you want anything decent and does not look at home in an industrial kitchen. There are good designs available from a number of German and Italian companies on ebay. Look for a T5 tube (this is the modern 15mm tube) and electronic HF control gear (instant start and no flicker)
Not sure which traditional kitchen fluorescent tube light you want. There used to be a 60w circular one or a standard batton with a diffuser however I see you are in Louth so try Wesco on Donore Road, Drogheda. If they don't have maybe they could get or direct you to where you could find one.