AOSP Keyboard on Stock Rom

As the above title really, I've been on CM roms with most of my android phones, and I really miss the keyboard. I'm trying to get used to a phone without root as we will loose Android Pay when it comes to the UK if it's rooted.

Anybody know of a way to install the AOSP Keyboard, or get the punctuation on long press on the standard Google one without rooting?

Cheers