If you have a full PPL then I don't see any issues.
For those with an Irish PPL(M), the answer is it depends! If they did the old old microlight licence that was issued in accordance with ICAO Annex 1, then I think they may be able to have the licence re-issued as they already meet all of the requirements (possibility that a skills test may be required)
If they hold one of the newer (30 hour) PPL(M)'s then they will need to complete the missing lessons/requirements between PPL(M) and the National PPL(A). Any revalidations with instructors over the years would be counted as well as logbook evidence of a qualifying cross country. Once that is complete, then a National PPL(A) skills test.
This training can only be completed at a National Flight Training Organisation (NFTO). (e.g. www.funfly.ie
Hope this answers your question.