It's always tempting to show just how knowledgeable we are about how to handle money when travelling in another country. But before showing off my own vast knowledge of the subject, I would first want to know a bit more about this trip of yours Oxnardjan.

You mention it will be your first trip to the UK and Ireland. Will it be your first trip to Europe overall as well? Do you plan to visit other parts of Europe on other trips after this? The reason I am asking is that if this is a one time, not likely to be repeated (to anywhere else in Europe) trip to Europe, then there really isn't any need for you to be looking at opening different bank accounts, getting different cards or finding out if your credit card charges currency exchange, etc.

For a one time trip, you just need the simplest solution to how to handle your money. If you are likely to visit Europe several times in the near/middle time span, then it starts to make sense to learn much more about the topic.

If it is a one time trip, I would suggest the following. Buy 100 GBP at home, who cares if it costs you an extra $10 to do so over other methods. The same with Euros, but only buy 50E. That should cover minor cash purchases for your 6 and 2 days respectively. Use your credit card for all major purchases/payments as you plan. Again, even if you are charged say 3% in exchange fees, who cares, over 8 days it will still add up to peanuts.

Getting the right cards and understanding how currency exchange works etc.only makes complete sense if you plan to visit Europe (or any other places in the world) on a more regular basis. A trip to a foreign country once every 3-5 years isn't worth the effort.

Iwildernova has given one piece of advice I would also stress. Make sure when using your credit card that you are paying in local currency, not US Dollars. Merchants etc. will often hand you the machine to enter your PIN number and you will see that before you do, there is a choice of paying in US Dollars or the local currency. Always choose the local currency. This is something called, 'dynamic currency conversion'. You don't need to really understand it other than to know that if you choose US Dollars it will cost you more.

Sometimes those who travel a lot tend to assume everyone does. I don't know why, other than you mention a cruise, (presumably from the US to the UK) and that tends to make me think this may well be a a one time thing for you.