What computer and programming skills can/should I learn during my vacation where I won't have an Internet access?

Maybe learn MS Office , PC Operations

Try, to practice creating a database, using my SQL or start with microsoft access. Make a search out of it. Because it is suitable in your line of work.

Basm Allah Alrahman Alrahim

buy any Photoshop Book and learn how to make Websites layout using Photoshop and buy HTML and CSS Book learn essential HTML & CSS Tags and elements