The best way is to find a good local keyholder and do it yourself using sites such as Holiday Rentals, Holiday Letting and Daltons Holidays as they spend thousands of euros generating traffic
Also friends and family, consider a scheme where if somebody gets you 3 weeks rental they get a week free or for half price
Get a good local information pack, a good website and put ad´s up in local stores in the Uk and golf clubs
Remember any agent will want to add a percentage to the rental which could make your property too expensive compared with owners that advertise their properties direct on websites
You will only pay an annual keyholding fee plus a local charge for cleaning and meet and greet which is passed onto the renter