I mailed a used Nikon d5100 to a friend in London and the damned UK customs stuck him for 150 pound tariff. I know Ireland is not part of the UK, but if you mail your lenses to a hotel in Ireland, the customs folks might stick you with import taxes.
Bob Yankle wrote:
As for a heavy tripod (and dare I suggest, your heavy lens?) you might consider mailing/shipping it to your hotel a few weeks before your arrival, then mailing it home afterward. When I made a trip to Yosemite National Park, we had bought so many souvenirs that we packed them up in a box and shipped it home via UPS. It kept the carry-on luggage to a minimum. I don't know what International Shipping costs are like (and I would definitely have it insured), but it's worth checking out.