@nailer, probably the best thing to do would be to pack it in a box first, so you will know how big the package will be, and how heavy. Then go down to the post office and check prices. If you are close to a threshold for weight, you can either leave a few things, or add up to the next threshold. You can also check that you have a suitable shape of box. That is what I usually do.
I have sent things from China to UK before. 5 days to UK port of entry and then 3 weeks for Royal Mail to get it to the address. I am not sure how long the Irish post will take.
If you are in no hurry, surface mail will be cheapest. But wrap everything water tight as it is rainy season is almost here, and things do happen.
The postal service is the cheapest and the easiest (At least for non air freight).
To enable their low prices there are some conditions. The main one being that you have to use one of their standardised boxes. This ensures effective stacking so more parcels will fit in a container. Like all shipments you need a statement of content. This has to be witnessed by a postal service official. So do not pack things because all has to be opened again.
For small shipment you can take your stuff to a post office that does shipments and pack it there in one of their boxes (They provide tape as well).
For bigger shipments you can call them and they will come to your house with several sizes of boxes and a role of tape. Then you will pack it under their eyes and they will do the rest.
General rule is: No liquids, no aerosols, no perishable goods, no plant and animal products.