Hm… use toilet in work. Toilet paper is free and you get paid for time spent.
I can also advise to get fuel card from www.motocard.ie which can save few cents in certain areas, however they are not always chepeast solution. Actually saving on buying fuel is not good, it wastes your time and makes you drive so total cost may be hire. If you buy Apples in Aldi instead of Tesco there would be more money saved. Also avoid roundabouts and traffic lights as they increase fuel consumption.
Go to Eastern Europe for medical help, hudge savings on dentists and drugs. If not into travelling use one of Polish medical centers, they usually charge a bit less and tend to take care of patients.
Buy on the internet all electronics, shipping a single computer mouse across europe is cheaper then buying it in PC World. Or any other shop in Galway.
Do not use planes and trains in Ireland, buses are cheaper and hitchhiking is cheapest.