How much work will you be doing in it?? If your doing a lot of late hours making noise having cars parked around the place your neighbors might kick up a fuss and contact the council. Just a thought...
Is there any services going through your lawn?? e.g Water, sewage, gas, ESB, telecom/choras? Would be handy to know before digging...
As stated before look onto proper drainage and damp proofing for the area.
Are you in the City or County? This might have some info for you...
http://www.corkcoco.ie/co/web/Cork County Council/Departments/Planning/Planning Guides
You might have to call into the county hall for some leaflets
"Leaflets PL.5, PL.6 and PL.7, which are available from your local planning authority, give details of the main exemptions"