If you have the LTE option, you can swap the SIM card to your android phone after pairing the Apple watch with your iPhone. You can then leave your iPhone at home and all notifications and calls will go to your apple watch.
To deal with the battery life issue, you can connect your apple watch to your android phone (or iPad if it's cellular) via mobile hotspot. I've done this with my S2 apple watch and a galaxy S8 so I know it works. This will drain your phone's battery but will save battery on your watch. Not ideal but it's the best way I can think of.