Version control design for automation framework - Git

I am a newbee to Version control

Client Requirement,

Client has three environments. Not like dev, test, preproduction. They name with unique names. They move code from any of the environment to production.

The application has many modules which is independent from each other. They give patches to modules seperately and release.

For example they can give patch a23 for module a, b25 for module b, c20 for module c for a release. some packages canot have patches also.

If they want to validate module a with a23 in env1 it should run and if it is env 2 also it should run. Then they will move to production.

I have to design test automation framework and design version control for this automation deliverable. I am totally confused as of how to give solution. Please help as it is very urgent.