Will Rooting android give me access to Google Play?
When your Android device is rooted, you should be able to flash images. There is a "gapps" package that contains the Google applications (like Gmail, ...) that is delivered with most AOSP roms, so you can flash that through recovery. 

If I'm not mistaken, this enables the Google Play Store on the given rom. I think the gapps package must be (somewhat) compatible with the rom it's being flashed on.

There are also separate apk files that you can install directly (without flashing), though I have no experience with those. And again, they probably must be compatible with the rom you're currently running.

Please refer to xda-developers.com for more information.