How to setup new official repository for a country?

I'm working on some network infrastructure and services projects in Timor-Leste. It's a newly developing country which doesn't have any kind of reliable or reasonable Internet connections. Along with my projects, I also want to push Ubuntu for use in govt, education, etc. But the country really needs a local repo server for Ubuntu to be considered by the govt or other organizations.

I can manually download and transport the data from a neighbouring country, but how do I setup the repo and get it in apt list?

PS: How many GB/TB for all four repos from MAIN?

Any assistance greatly appreciated!

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Jkn