Hi John,
Do you own the site and are looking for planning permission before selling? Its not really clear from your post.
You will have to pay a fee for a planning application to be determined. You will need site plan, block plan, elevations, floor plans etc. There will be a time limit attached to any planning application approval being implemented (3 years in the UK, not sure about Ireland anymore, but the planning authority will be able to tell you). In Ireland there is a 3rd party right of appeal, be it from neighbours or anybody else, who could appeal the decision to An Bord Pleanala. If you give some more details may be able to advise further!
Runner1 (Planning Officer, currently working in UK)