I'll offer another incomplete answer. First of all, asking whether un-named meds you're prescribed in the U.K. will be available using your U.K. scrip--or even available at all--is impossible to answer. You'll need to specify the medication in question along with the country, and this might attract a useful answer.

Second, in at least some of those countries there are lots of counterfeit medications, along with meds that have been mis-handled or are well past expiry. Personally, I buy my travel meds at home where I know what I'm getting--and won't have to interrupt a trip to go off in search of medications, then wonder whether whatever I bought spent a month in some warehouse in the tropical heat.

I make exceptions when traveling to places where I trust the distribution channels and for drugs unavailable at home, like Coartem. However, in most such places the prices are as high as they are at home anyway, so there's no advantage to waiting.

Third, certain meds within your general categories are not licensed in all countries, and may even be more expensive when they're available. I always think of Malarone in this connection, but with the advent of generic versions I'm not sure whether this still applies. In any case, it's worth being specific, at least when it comes to anti-malarials and other meds where the specific formulation matters greatly.

Hope that's helpful.

Mark