I don't think they'd take the prepaid cards, but that wouldn't be you're best option anyway.
you have to leave a credit card print with most hotels and cruise ships, incase you run up a bill and disappear.
If you took the preloaded card option you'd have to load it up with your own cahs first, just incase you later used room service etc. Then, if you didn't, you'd pay charges when you withdrew the cash you put on.
the best thing to do is get a 'commission-free overseas' credit card. the post office have one, nationwide's I believe is still free outside the EU, and I think Santander have one.
That way, you'd only have to settle up your CC bill at the end of the month if you actually used it.
You need to be careful to pay the balance off each month though.
with all the delays etc over the ash cloud and BA strikes, having a card to fall back on is a really good idea.