Thank to all of you for your help. This is the first Apple product I've ever bought so I got a lot to learn.
An iPad battery comes, more-or-less, fully charged. There's no need for any special precautions. Charge as often - or as infrequently - as you like. The iPad is 21st century, so none of those old precautions apply. Apple want you to be happy so they used some ultra-sophisticated battery charging electronics in the iPad. Leave it on charge all day - no problem. Let the battery go completely flat - no problem (though you'll need to charge it before you use it then, even Apple can't control the Laws of Physics - yet!).