Just about every Android tablet has GPS (I've only seen one that didn't).
Apple only supply GPS with their cellular capable model iPads.
But do you really need GPS in a tablet?
The only features that can use it are Follow-me flight and resetting the home point to the current location of the controller.
Neither is very commonly used and there are alternative options that work just as well.
Well, following all the information and recommendations I settled on a Nexus 7 and picked one up for £35. Now I have DJI Go, Litchi, and DroneDeploy all on the same tablet. And as soon as the weather here breaks, I plan to put it to the test... thanks for all the feedback