Marks and Spencers have recently brought out both a sourdough margarita and garlic pizza bread!
At £4 each I found these particularly expensive but well worth it, I have never seen a gluten free garlic pizza base, only baguettes. The base was delicious and it did not skimp on the garlic like the baguettes do! My only disappointment is that they were only small, I wouldn't recommend sharing between more than two people.
Let me know if you've tried these or found something better.