Well, for starters you can install a new launcher on it, if it's running 4.0/+ then get Apex Launcher, it will give the look and feel of an AOSP tablet, but installing a new launcher won't change theme, as in if the statusbar is themed, it's appearance won't change. First off go to settings on your tablet, security, then enable unknown sources for installing apks. next, download ICS Gapps zip from internet (use google, you will find it in a sec), place on root of device, then flash from recovery. If the tablet's recovery won't let you flash then I guess you won't be able to put play store on it unless you use ADB which I have no clue about. You can get Apex Launcher on the tablet without play store though, just enable unknown sources, place the apex launcher apk from the internet on root of device then install from a file manager.