We got one done by http://www.atticmasters.ie/ last year and it went very well, excellent quality of work. Price was around the 20k mark including VAT and some additional work (replacement of bannister + upgrade of velux windows).
The guys were done within 2 weeks, were very clean. Make sure to put some work into specifying your insulation - we obsessed about it at the time but it worked out very well.
Try Danny Carroll 0877503617, an excellent builder with great attention to detail and very reasonable. I havent had my attic done although i did get a quote from him. However, he has done alot of other work for us and also our neighbours.