Do you have an Irish pension? If youa re asking about a pension based solely on GB contributions, you will have to contact DSS in GB regarding entitlement to an GB pension
If you were in registered employment and paid National Insurance Contributions in the UK you will have some entitlement to some pension from the UK but if you receive a non-contributory OAP here in Ireland, then any UK pension may reduce this. If you receive a contributory pension, then you can get both. Did you work for many years in the UK and was your employment registered?