Contact the EAST COAST SURF CLUB (ECSC) - details below. The ECSC primarily operates as a surfing and networking social club for surfers of all ages and levels of experience. Its not essential to have a board; club members can borrow the club boards or rely on the generosity of fellow EcScers but if you want to go regularly, you do need your own wetsuit, gloves, boots and hood (for winter). There is seldom surf on the east coast so we generally go to Sligo at the weekend for good waves and general decadence. There is always space in someone's car and we operate a very lively on line forum for members to keep in touch which acts as a virtual club house.
Ok, heres a few surf spots close to Dublin. Waves aren't going to be great, but everything I will mention here is definetly surfable.
Killiney Beach. Probably one of the best on the east coast. Needs a low/mid tide and easterlys. South swell is needed, as always for dublin, etc(!)
Magheramore, just south of wicklow. Best spot near Dublin to surf. A nice bit better than Killiney. Think the carpark is closed now, but you can still park on the side of the road. If theres a southerly swell and easterly winds, go here. about 6 years ago