The pound is the currency of the UK - which includes Northern Ireland. Notes available are £5, £10, £20, £50 and £100.00. Coins are 1p, 2p, 5p, 10p, 20p, 50, £1 and £2. There are 100 pence to 1 Pound.
In Ireland the currency is the Euro - if you are coming from Europe you will not need to change any money over. One Euro consists of 100 cent. Notes available are 5 Euro, 10 Euro, 20 Euro, 50 Euro, 100 Euro, 200 Euro and 500 Euro. Coins are 1 cent, 2 cent, 5 cent, 10 cent, 20 cent, 50 cent, 1 Euro and 2 Euro.
The exchange rate varies from day to day and for an exact amount on the exchange you would need to check with your bank or exchange. On average the exchange works out as £1.00 = 1.46 Euros.
If your taking credit cards, then Visa, Mastercard & American Express are widely accepted - for anything else you will need to check with the place you are purchasing from.