Is anyone else getting second-hand anxiety just by reading this thread?!!!
Assuming it is real (considering it's MN so anything is possible), the level of ill-preparedness is disturbing. Why go on an overseas holiday when you don't understand currency conversions? Why go to a third world country where nobody speaks english? OP admitted to learning difficulties and struggled with tasks in english (bookings, refunds, travel research etc) so going to a country where you can't read a single sign seems like madness.
Some other considerations, and not attempting to be a downer, but these are realistic situations that everyone must be prepared for on a holiday. Worth delegating to DS if necessary.
Do you know how to get internet there? Will you be using your phone and if so, which apps and how many GB of data?
What happens if you lose your passport and/or money? Do you have digital copies of your passport saved to a Cloud device or a physical scan of it elsewhere? Do you know where the British embassy/consulate is in case of emergencies?
Do you have medical travel insurance? What if someone gets seriously ill or in a car accident and needs hospital treatment? Does the insurance cover repatriation flights back home in case of a serious incident?
Do you know the rules of eating and drinking in a third world country? Things like avoiding ice cubes, anything prepared with tap water or raw dairy (salads, dips, cream, cakes etc), using bottled water for teeth washing and rinsing your toothbrush?
Do you have the payment methods available in case of travel disruption? If someone gets food poisoning or if there's an accident at Heathrow (eg today) or if you miss your flight due to traffic, can you purchase alternate flights from a foreign country and possibly without a laptop? If you only take cash, you may not have enough for an additional flight or accommodation.
Tunisia is not a great country and whereas you can lower the chances of getting mugged by staying in the hotel, the chances of food poisoning or travel disruption are always present.