Hi John Paul,
Yes, your passport is fine for travel to Ireland.
The UK and Ireland are both part of the Common Travel Area (CTA), which allows free movement between the two countries. As a UK citizen, you do not need to have a specific minimum period of validity on your passport to enter Ireland. Just ensure your passport is valid for the duration of your stay. Since you have 4 months left on your passport, you're good to go.
Let me know if you have any more questions regarding your upcoming trip and I will do my best to help.
Cathaoir