Hello Pinchy,
I am a freight forwarder. All of the suggestions by the posters are valid ones. However, if the weight of your proposed shipment is only aprox 600 kgs, it is hard to imagine filling a 20' container, never mind a 40' container.
If you want to PM me or post the following details in this thread ;
1) Origin of the cargo (if you have a postal code, that would be great)
2) Point of delivery in Ireland
3) Individual dimensions (LxWxH) of the piece(s)you intend to ship
I can have a look and see what the options are.
Best regards,
Rudolf289