I shoot with Canon and *love* the 100mm macro lens (I don't have the L). I also use the 70-300mm telephoto zoom and the nifty fifty and am very happy with both of those. I occasionally use the kit lens, but usually only if I am really desperate for a wider angle than I can get with the others--I find that in general it's just too soft for my taste. I would never use the kit lens for macro photos but have used the telephoto lens for a macro-look.
If you are very new to photography, jumping straight into the macro lens will probably be pretty difficult--shooting with a macro lens has its own set of challenges (like lighting and dof). On the other hand, if you have been at it for a while and are looking to step it up, then the macro is probably the way to go. If you're unsure, I'd go with the telephoto. If you find yourself getting as close as you can to the subject with the tele and setting your zoom out to 250-300mm, *then* I'd think about the macro lens.
Have you checked out the website photo.net? There are tons of informative articles and forum discussion there on equipment and purchase strategies.
Enjoy your trip to Ireland!