Our highschool library had gamebooks. Lots of the fuckers. I'd read through every 'choose your own adventure' book in the little book mobile that visited our primary school and stuff like Fighting Fantasy seemed like a hell of a step up.
There was a series they had at the highschool called 'Lone Wolf'. Fighting Fantasy was a framework more than anything. There was a world built up in them, but it was accidental. There was no over-arching story told and frequently books went off and created totally new settings. But Lone Wolf was different. You played the same character in each book and as you moved from one adventure to the next you gradually improved your skills, defining yourself into a role depending no the decisions you made.
Anyway, yeah, they're all available free and legal on the web.