JamesJim - if you have to concentrate on singing and you do so - continue with it. It's a good opportunity to learn singing. You will know how to sing when you don't have to concentrate on it any more. You'll get another opportunity to learn playing your guitar once you are able to simply sing without really noticing and then listen to what your guitar is doing. That's how it happened and still happens to me. Don't try to force something, simply go on, GO ON.
And don't think you'll learn faster by clinging to a song until it's perfect, then to the next and so on. Cling to a song until you can do it by heart (i.e. you KNOW it. Knowing songs at all is much more important than doing them good.) And then take the next one. This will keep you from being bored by your own music and your learning will be faster because of your own interest. Your audience? You can outperfom any perfect player by simply knowing two songs more than he does. (The right ones of course *grin* in fact this will take you the effort of learning ten songs more, but what's difficult with it?)
Joerg