The slight variation in your name might cause a problem at the airport. I've put 'Chris', instead of 'Christopher' before now, without any problems but, as Cockroach suggests, it might be best to check directly with the airline.
Assuming you're a UK citizen, you don't require a passport at all to enter the Irish Republic but you do require photographic ID. (Each airline has its own rules but even the strictest, Ryanair, accepts an EU driving licence).
Additionally, only a few countries require you to have 6 months on your passport when you visit them. None of those countries is within the EU. (EU legislation obliges all member states to admit any EU citizen, as long as they've got proof of citizenship (such as a passport or national identity card) throughout the validity of that document. i.e. you could turn up at the immigration desk of Spain, Italy, Latvia, Slovakia, Ireland or any other EU country on the very last day of your passport's validity and still be guaranteed entry).
Chris