Marion, get a small PA. From this post and previous ones you've made regarding gear, that seems most helpful for what you're doing. Others may be able to verify this, but I believe you'd get superior separation in the channels from a PA as opposed to an amplifier. You don't want your instrument to step on your voice or vice versa.
And, please remember, you're buying gear and evolving as a musician. As you progress, you'll be selling old stuff and buying new. So get a nice small second hand PA and see how it does! Sell it when you're ready to move on!
Enjoy yourself and the best of luck to you!
Ed