Yes, banks do charge a fee. I haven't done it for such a long time. As I recall it can be 3% or a little more. Take a look at my "Money" page and click through to Oanda for exchange info.
You might look into an EF Travel card. They are used similiar to a credit card but you deposit money into them and can have money deposited into them by others back home should you get into a jam. I have one and I set aside a specific amount each month which I deposit into it. That keeps the money "locked up" so I don't spend it.
You can use them at ATMs and, like credit cards, all over Ireland, as well as other places.
If you live in a town with a Compass Bank (compassbank.com), you might consider opening an account with them strictly for travelling. They do not charge any ATM fees to use their card anywhere worldwide. If you are charged a fee, you submit the ATM receipt to them on your return, and they reimburse you!
Their exchange rate is also extremely reasonable (equal or less than our credit card exchange rates). We opened an account with them before our first trip to Ireland in 2007. There is no minimum balance required, so we just keep it as our travel account. We deposit funds to it prior to travelling and then use the ATM card as we need cash on our trip. Since the interest paid on our regular savings account at our credit union has been so low lately, we've been pre-funding for this year's trip. Like Bit's card, the money is out of sight, out of mind.