In your situation I’d use membrane – as wide as you can get to reduce the number of joins, and possibly lay cardboard under the membrane – especially under the joins. Make sure you level the ground beforehand otherwise you will be constantly tripping over lumps and hollows (I speak from experience!) and don’t be surprised if you have to free it from encroaching weeds (especially at the edges) every 6 months or so…
Compostpope