Zones and postal methods
A zone is a set of countries you post to on the same terms. Your own country is already one. Add a Europe zone, a rest-of-world zone, or as many as you need.
A country belongs to one zone only. Tick it in a second zone and it moves there. Mark one zone as everywhere else and any country you have not listed falls into it; leave that unmarked and those customers are offered no postage at all, only collection if you allow it.
Methods belong to a zone
Each zone has its own postal methods, and each method prices every group itself. That is how a tracked service costs more than a standard one for the same booster box, and how posting to Europe costs more than posting at home. Untick offered at checkout to hide a method without losing its prices.
A zone with no methods offers no postage. That is a valid way to say "we do not post there".