[RPG] How to get the most languages with the fewest level investments

There really isn't a way to gain a spell book as a gish type class. Wizards don't yet^[1] have a viable melee archtype (though building one wouldn't be too hard, we have some models in the cleric domains).

There are however other ways to handle the problem you are facing.

Since your primary issue is in background type information and characterization, I would handle the majority of this mechanically by writing a custom background. This would give your proficiency in history and arcana (or another skill if you get it from your class), and a book that has arcane writings in it. Discovering the secrets of this book should be related to one of your character's BIFT.

Whether or not the development of the story around the book ends up providing you any future mechanical benefits is kind of up to you and your DM to hash out, but it seems like a very solid starting point for a new character in a game.

_{[1]: This answer was written before the Bladesinger archetype was published.}

Omniglot

The writers for Disney's Atlantis, Klingon from Star trek, etc. All created languages during the course of their creations, and most of them are available on this site, called Omniglot. At the bottom of some Omniglot pages there are fictional fonts that you can use for writing that should fit what you're looking for. Personally my favorite is the Daedric alphabet from The Elder Scrolls games, but there are a lot of languages and fonts to browse on this site.

For a nice overview of fonts available from Omniglot, see its fonts page.

Dieter

Dieter is a website made by Dieter Steffmann that hosts a wide variety of fonts. While I personally don't feel that it has a lot of fantasy fonts similar to Omniglot, its selection of fonts covers a wide variety of text types and is worthy of mentioning as well.

Thanks to @Storyteller for the suggestion.