I managed to get a refund via steam and instead purchased the game through the Rockstar launcher.
So I’m now using the Oculus setting on vorpX.
I managed to find the in-game menu and try the three viewing options (immersive, cinema and full Vr) and with all of them I can see the edge of the screen.
I assumed I was in cinema mode previously but I wasn’t. It looks pretty much the same apart from in cinema mode I can see chairs too!
I feel like I’m missing something obvious.