Hello Locks, it is definetly the case that you will not be able to book optional excursions before your holiday. Your optional excursions will still be bookable through your tour manager while you are on holiday. As for payment, a credit card should be an acceptable form of payment. If for any reason your tour manager will not accept a credit card, there are cash machines where you will be allowed to withdraw some money. However, the optional excursions are not that expensive, and I would still advise that you exchange some money prior to your trip to give yourself the freedom to do and buy what you wish. Cash is always the easiest option, and you can keep any extra cash that you do not want to travel with in your hotel safe.
I hope this information has been helpful and if you have any further queries then feel free to email me.
Kind regards
James, your editor